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Ongoing internet dropouts HFC NBN

G'day folks

Just wondering what is an acceptable level of internet dropouts for a HFC NBN connection? An Optus tech today suggested that NBN considers up to 10 per day as reasonable and not needing further investigation!!

Since about the beginning of April I'm averaging 2-3 per day, each lasting about 3-5 minutes. Fail pattern usually the same: no internet; then on the F@st 5366TN-A router the phone, internet and WAN lights go off; then CM 8200 modem lights go off and it recycles; then router WAN light comes on, internet light flashes, becomes stable, and phone light comes on. Router logs show lots of "PPPoE error: timeout" entries.

In the router settings, the 'Internet Connectivity' page is usually showing:

Connection type DHCP
Addressing Type DHCP.

During the above failure process, it shows:

Connection type PPP
Login hidden
Password optus
Addressing Type DHCP

There is a 3G/LTE Backup page, which I have set to Off, because this router does not have a SIM option, despite this page/firmware suggesting it does. When it is set to ON, the Status shows DOWN in red letters.

The router logs show that prior to the beginning of last month, there were PPPoE errors recorded, but they were usually less than a minute or two, and less frequent, so not so noticeable. I wondered if the worsening is related to the router going through the motions of trying to get a 3G/LTE connection when the line drops internet, and this delays the usual recovery from a brief line dropout? This would mean that the router is not complying with my setting the backup to "Off".

After each failure cycle, the WAN IP address swaps from one in the 49.198.x.x range to one in the 175.36.x.x range or vice versa. The router firmware version is 105.

Two visits each from NBN and Optus techs have tried new modem and RF cable isolator, new router, and various changes to ethernet cables and power cable connections and modem/router box locations, but faults persist. I have also tried various combinations of LAN devices being left off the network, and set all LAN devices to static, fixed IP addresses (very easy to do thanks to the 5366), and turned off "Port Forwarding" and "UPnP Ig" in the router (the last two for security mainly).

Optus tech indicating fault is not at my end, and referred back to NBN again. However, I wonder if it is due to Optus locking DNS resolution to their own servers only. I know there were problems with Optus DNS around the time these dropouts worsened. The infosec site "risky.biz" had to move to another service provider because Optus DNS servers were not resolving that site at all, on any Optus fixed or mobile services. Interestingly, I was able to get access to that site during those troubles by setting an additional DNS server address (1.1.1.1) in my computer network settings, which is apparently not supposed to get through the Optus router, according to other posts here.

Does any of this sound familiar to anyone? Anything else I can try?

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Re: Ongoing internet dropouts HFC NBN


An Optus tech today suggested that NBN considers up to 10 per day as reasonable and not needing further investigation!!

There is no way that 10 outages per day can be considered acceptable. They may wish it was, but it


Since about the beginning of April I'm averaging 2-3 per day, each lasting about 3-5 minutes.s not.

I would accept that outages happen occasionally, but certainly not 2-3 per day.

As the NBN is both internet network and phone network, just on the basis of it being the phone network makes that level of dropout completely unacceptable.


After each failure cycle, the WAN IP address swaps from one in the 49.198.x.x range to one in the 175.36.x.x range or vice versa.

49.198.x.x is only a mobile IP range as far as I know, so I would not expect you to ever get that IP unless it actually talking via mobile at some level.

Connection type PPP
Login hidden
Password optus

The fact that you are seeing login/password details would imply that its found something to try and log into that is not through the WAN port. With NBN HFC the normal connection type should be DHCP as the CM 8200 is the modem and what it passed on to the 5366 is straight WAN connection, with no login required.


Router logs show lots of "PPPoE error: timeout" entries.

That is not unusual. Its not necessarily an indication of mobile backup attempt. When the 5366 is fired up it checks both the WAN port and the DSL port for an internet connection, and I'm betting that most (if not all) of those errors are just it confirming that there is nothing plugged into the DSL port, which there shouldn't be for NBN HFC.


I wonder if it is due to Optus locking DNS resolution to their own servers only.


I would rank that as a strong possibility. I've found Optus DNS so unreliable that I haven't used them for many many years, even pre NBN.

I was able to get access to that site during those troubles by setting an additional DNS server address (1.1.1.1) in my computer network settings, which is apparently not supposed to get through the Optus router, according to other posts here.

Nope, its the opposite. If it didn't get through then that would be a problem as it would constitute DSN hijacking which is a big no-no.


Anything else I can try?

Do you have any other router lying around, and that allow the DNS setting to change?

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Re: Ongoing internet dropouts HFC NBN

Thanks for your quick reply YetAnotherAcc

I would agree that occasional outages are inevitable, especially given the Malcolm's Technological Mess approach we have been saddled with. It is the time taken for the system to get back to normal that is the biggest hurdle, and I am keen to minimise anything that extends that delay in recovery.

The possibility that the errors showing during failures are due to the router trying the DSL port is interesting. Would it know to change the connection type to PPP and present the Login and Password while trying this; i.e., not relying on the request for credentials coming from whatever system it is trying, to know what to present? If it IS trying this port, perhaps a firmware change that could tell it not to bother trying anything else that it has not been specifically set up to have available might be helpful in streamlining its response to failure of signal. Maybe just a setting with an Off button like the one for the 4G/LTE alternative connection?

Regarding DNS problems; I wonder if they could account for complete internet dropouts, rather than just failures to connect to specific sites? Is there something in the upstream system that causes a complete dropout if there are too many errors? Or something in the router that reacts to too many errors by trying to reset the modem or the connection?

I am more regularly using the site "whatismydnsserver.com" since setting up alternate DNS servers (Cloud Flare 1.1.1.1 and Google 8.8.8.8) on my computers. I am seeing some Google and Google LLC servers listed along with the inevitable Optus server, suggesting the router is not blocking these. I will try to set up alternate DNS servers on all devices and see if that reduces outages.

I still have the old Optus Cable modem router (Netgear CG3000-2STAUS) but when I connect its WAN port to the NBN modem, it doesn't make a connection. I presume there may be some settings I have to change inside?

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Re: Ongoing internet dropouts HFC NBN


Would it know to change the connection type to PPP

Each connection port would be associated with one or more connection types, and I'm guessing that because the Optus modems are designed to handle both standard ADSL and NBN connections automatically (i.e. without the user telling the modem if they are plugging the DSL port into an ADSL service or FTTN service) the modem will go through the connection types in a specific order. With FTTN & FTTB the connection type Optus is expecting is IPoE (aka DHCP), so the fact that we are seeing PPP would indicate that its typing to connect as non-NBN ADSL just in case that is available.

and present the Login and Password while trying this; i.e., not relying on the request for credentials coming from whatever system it is trying, to know what to present?

When you mentioned initially that you saw login & password attempt, I fired up my 5366 and checked it logs and did not see any password & login attempts, only PPP. This is what I would expect as logical order.  Given that you got a 49.198.x.x I would expect that that PPP login & password attempt was for the mobile network. That would imply that your 5366 has some mobile backup hardware. My 5366 does not seem to, nor is it supposed to.


If it IS trying this port, perhaps a firmware change that could tell it not to bother trying anything else that it has not been specifically set up to have available might be helpful in streamlining its response to failure of signal. Maybe just a setting with an Off button like the one for the 4G/LTE alternative connection?

I don't think they would want to do that because it would mean yet another check that they would need support/user to do when troubleshooting.

Regarding DNS problems; I wonder if they could account for complete internet dropouts, rather than just failures to connect to specific sites? 


I doubt that, though of course its not impossible. The whole point of nominating primary and secondary DNS server is for just such occasions, when one DNS server fails, it is supposed to switch to the other. If DNS failures are causing complete internet loss, it could also be a firmware problem preventing DNS fail-over from working as intended.

something in the router that reacts to too many errors by trying to reset the modem or the connection?

If that is the case then it is very bad design. Even without an internet connection the 5366 should still be usable as either a media server or just as a local router/switch, and if its constantly rebooting to try and get an internet connection then it fails for those scenarios.

I still have the old Optus Cable modem router (Netgear CG3000-2STAUS) but when I connect its WAN port to the NBN modem, it doesn't make a connection. I presume there may be some settings I have to change inside?


See if there is "WAN Connection Type" option anywhere. It should be DHCP/IPoE/Dynamic IP or something similar.

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Re: Ongoing internet dropouts HFC NBN

Thanks again YetAnotherAcc

Apologies for not being clearer regarding the PPP settings and IP address changes.  My connection is HFC. The PPP, Login and Password only appear in the Internet Connectivity page in the router GUI during failures. They don't appear in the logs. The only connection related log entries are the PPPoE errors I noted above, and the rest of the logs are mainly lists of DNS name resolution failures.

Sometimes there can be an address listed as failed DNS multiple times within a minute, as if it is continually re-trying unsuccessfully, but this does not lead to a failure. I can't actually see any consistent log entry or activity related to failures.  The only possibility might be that I have thought that on some occasions when I have woken my phone up, it gets the first internet page I go to, and then the dropout occurs, but this is not consistent.

The IP address is a genuine change after failures, and stays connected for the duration until the next failure, when it usually switches to the other range. It is currently 49.198.xxx.xxx, confirmed by whatismyip.com, and has been that since the last failure at 11:45 this morning.

When I get a chance I will fire up the old modem/router and have a look around in its settings.

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Re: Ongoing internet dropouts HFC NBN


@frankus333 wrote:

Apologies for not being clearer regarding the PPP settings and IP address changes.  My connection is HFC. The PPP, Login and Password only appear in the Internet Connectivity page in the router GUI during failures.


I should have pickup on that as logs should not contain passwords. It also didn't help that when I looked at the connectivity page on my 5366 (which is not internet connected) is did not show any username & password fields.

I just had a bit of a play and finally got those fields to show by actually connecting it to my network. There are lots of these UI problems with the 5366 which make it frustrating to use.

So it may be that all those PPP errors in the log are actually from the WAN port and not the DSL port, I just can't tell anymore.


They don't appear in the logs. The only connection related log entries are the PPPoE errors I noted above, and the rest of the logs are mainly lists of DNS name resolution failures.

You should set the logs to "Debug or higher" as it gives more info about what is happening.


Sometimes there can be an address listed as failed DNS multiple times within a minute, as if it is continually re-trying unsuccessfully, but this does not lead to a failure.


All the gibberish domain names like xpywetp or whatnot are DNS probes and are the main way it checks if the connection is still active and are always invalid domain names. Seeing a bunch of those in succession is normal.


The only possibility might be that I have thought that on some occasions when I have woken my phone up, it gets the first internet page I go to, and then the dropout occurs, but this is not consistent.

That could be your phones connection caching/timing out, and not necessarily the modem losing the connection. The only way to know for sure would be to correlate the phone timeouts with the modems logs and see if the modem reports an internet reconnection at the same time. 


The IP address is a genuine change after failures, and stays connected for the duration until the next failure, when it usually switches to the other range. It is currently 49.198.xxx.xxx,

This part has me confused as my understanding is that the 49.198.xxx.xxx range is only used on the Optus mobile network, I guess that is not the case.

When you're on 49.198.xxx.xxx, do you get your full/normal speed? Can you do a speed test when you are on 49.198.x.x and 175.36.x.x?

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Re: Ongoing internet dropouts HFC NBN

Thanks YetAnotherAcc

I always view the logs on the "Debug or higher" setting. The DNS name resolution failures all look like proper addresses. I use Linux, and a set that appears regularly are "_http._tcp.security.ubuntu.com" and "_http._tcp.launchpad.net", twice each within the same minute, when my computers check for updates.   The check is successful.  Another regular one is "netmon-control.dropbox.com".  There are various others, and they all look like regular domain names. I haven't noticed any weird entries.

Logs also include regular TR-069 iniated and closed; usually two of each after each failure, and sometimes at random times between failures.

I may be confusing myself with the phone wakeup triggering the failure observation, if the first page I get is a cached page, and the failure happened to be already in progress when I woke the phone up. It is probably not the phone connection timing out, as I have just woken it up. It is definetly an internet failure, as this is confirmed by other pages attempted unsuccessfully, and other devices not having internet at the time. I will try to analyse this a bit more closely if it continues to happen.

I have a log of speedtest.net results, and both the IP address ranges usually show normal speeds; at least 46Mbps down and 18Mbps up. The tech indicated that the swapping between these IP ranges was normal for this connection, but he didn't know much about it.

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Re: Ongoing internet dropouts HFC NBN

More info for interest:

I tried the old Optus Netgear router, and the WAN port shows no connection, even when connected to the modem, and even after router reboot. I'm guessing the presence of the internal modem is preventing it from seeing anything else. The Cable Connection just says it has not signal; check RF cable.

What I found interesting is that while the new 5366 router was disconnected, its logs showed the disconnection, but it did not seek other connections; no PPPoE errors showed up, until I reconnected it to the modem. It then showed just two PPPoE errors, the reconnected IP address (now 175.36.xxx.xx), two more PPoE errors, and then the TR-069 initiated and closed (only one of each this time).

Not sure if that is useful info to anyone, but there it is.

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Re: Ongoing internet dropouts HFC NBN

In the old router, the WAN connection type was listed as DHCP Client. Releasing and Renewing the connection did nothing to help it connect.
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Re: Ongoing internet dropouts HFC NBN

Oops; found a setting in the old Netgear router that allows for "Always use WAN ethernet connection", so I will try again when I can disconnect the network.

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