Over the past month or so I've had extreme difficulty connnecting to anything via our Optus NBN connection (prior to this it was working quite well) - there were no changes to hardware or software on my side that could have caused this and ALL devices have this problem (phones, tables, TV boxes, laptops, etc). The odd thing is that when I connect to speedtest.net it seems to indicate excellent speed (close to 100 Mbps download and upload around 30 Mbps) but even connecting to local websites like smh.com.au is painful as it times out or can't load the images. I've contacted Optus support several times and the usual suggestion is to do a hard reset on the MODEM. Sometimes this has a momentary improvement but then quickly I end up in the same situation where I can't connect to anything.
What I have noticed recently though is that if I connect via a VPN (e.g. via a paid subscription to ExpressVPN or via my work VPN) then absolutely everything works fine via the VPN-connected computer i.e. I no longer have any problems connecting to any external websites (the same is true if I connect via VPN on a phone). The downside is that then I can't connect to anything local e.g. printer and other WiFi devices. The other problem is that many of my devices can't connect via VPN and so they still continue to have connectivity problems. That speedtest.net reports high speeds and no dropouts suggest that this isn't a hardware/software problem on my side and the VPN connection suggests that packets can get through ... so why can't I have connectivity without the VPN? Is this some problem with the Optus DNS? I was hoping to change the DNS in the MODEM but there doesn't seem to be a capability to do so via the admin window - ugh!
You're unable to change the DNS settings within the modem itself.
You should be able to change your DNS locally (on the device you're using)
You could try Google or Open DNS.
Really, you shouldn't be required to fiddle with your DNS settings. There must be an issue on the Optus end.
Have you tried running a trace route to one of the sites you're having issues connecting to?
Thanks for your post Dan_C - that was very helpful (sadly no solution yet but hopefully closer to understanding the problem).
That's a really good point regarding traceroute (I'm on a mac) - I neglected to try that. I just did this and I think perhaps I was too quick to blame the DNS - it seems to get the correct IP address of the host I request (or at least it is consistent with what I get via VPN). I guess this also explains why entering a manual DNS (e.g. the google one or the one provided by ExpressVPN) in my various devices doesn't seem to help with connectivity (much to the annoyance of my son trying to log in to his games on the X-Box).
Anyway, going back to traceroute, after getting the IP address from the DNS it then goes to the correct gateway (or at least the one that is in my SAGEMCOM device info) but then times out a lot while running the traceroute. Going via VPN obviously goes via a different gateway and it doesn't seem to time out as much (and connects to virtually 100% of the pages that fail if I don't go via VPN).
Sadly, I'm not a network engineer so this has all got me a bit stumped. It's also bizarre that connecting to bing.com and google.com seems to work a high percentage of the time but any of the links that are offered after a search will fail if I try to view them. Basic local sites like smh.com.au fail most of the time and when they do finally come up it is then a struggle to actually view any of the news articles.
That's okay. My advice is based on my own research
I wouldn't call myself an expert either.
I could always raise a referral with our NBN case management team? They'll give you a call and run through some troubleshooting in real time.
If that's of any interest, send us a private message. I'll need your full name, DOB, account number and best contact number.
I contacted Optus again today and they said they would escalate the issue with their case management team - hopefully they can help to resolve the issue. If I find out anything more I will post the results here.