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ntchebykin
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Optus 5366TN Nat Loopback Issue (Hairpin)

Hi Team,

I have just received a new modem to replace my old broken one, and all is working well, except I seem to no longer be able to connect to my internal home control app (Homeassitant) via the web address. I believe the modem is missing a NAT Loopback option (aka hairpin). 

Is there a way to enable it? Or is there a workaround?

Nik

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7 Replies
YetAnotherAcc
Respected Contributor
Respected Contributor

Re: Optus 5366TN Nat Loopback Issue (Hairpin)

There is no NAT Loopback option. That is a known issue.

Is there any info on port forwarding for the Homeassitant which you can try?

 

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DavidHarvey
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Contributor

Re: Optus 5366TN Nat Loopback Issue (Hairpin)

A manual entry in the hosts file should fix the problem. The 3864 performed Hairpin by default but not only is it not there by default for the 5366 the settings can only be viewed and not added or edited. The hosts file solution will only work on those wired or wireless machine with connection only to the Sagemcom. Regrettably most phones have host files that can't be accessed. Such is life.

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jimmyct
Occasional Contributor
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Re: Optus 5366TN Nat Loopback Issue (Hairpin)

Yeah. Same here. I cannot access HA from internal network. How do I edit hosts file?

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DavidHarvey
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Re: Optus 5366TN Nat Loopback Issue (Hairpin)

@jimmyct you edit the hosts file in W10 with Notepad run as administrator.

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Rixx7
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New Contributor

Re: Optus 5366TN Nat Loopback Issue (Hairpin)

Hi, I've had the Nat loopback for months since I received the new fast ! Modem.
I did some testing today and am pleased to say that this has been fixed. I can now access my external dns sites which live on my local network from within the network!Finally....
Thanks Optus
Kartika
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Re: Optus 5366TN Nat Loopback Issue (Hairpin)

Glad to hear that @Rixx7. We appreciate the positive feedback 🙂 


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I’m part of the Yes Crowd team, employed by Optus to help run our online community. This guide explains how everything works on here and you should also check out our Community Guidelines.

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Rixx7
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New Contributor

Re: Optus 5366TN Nat Loopback Issue (Hairpin)

To put my above comments into context, this was the situation.
Web sites and Virtual Machines which live within my local network and have an external dns addresses (for external users)
cannot be accessed from within my local network using the external address.
Some can, via local IP address, however I have 3 different subnets which I work between, so this was not a solution.

The Web sites and Virtual Machines could be accessed externally from outside my LAN on any other network connection or mobile.
This indicated that my port forwarding is working correctly for inbound traffic but outbound is either being blocked by the
DNS Servers, WAN firewall or other NBN higher powers!

This all pointed to a hairpinning (or NAT loopback) restriction using the Sagemcom FAST5366LTE-A.

This is not a local firewall issue as all sites worked perfectly with the previous Optus Sagemcom f@st3864 Modem Router and
then did NOT work using Sagemcom FAST5366LTE-A Modem Router withing the local network.

As mentioned, from the 15/04/2021, this has now started working! Access to all external VMs and sites on my local network can be accessed via their external addresses internally.
clearly an Optus update has been applied to the router or the pipe.
This has made my administration of these sites so much easier.
Thanks again.

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