Weird Hub3 crash in modem mode with ASUS RT-AX88U

[jrb2021]

Hitting a really weird issue with Hub3 in modem mode, connected to an ASUS RT-AX88U router (with Merlin firmware).  It works absolutely fine, except for one URL which I use to remotely login to my work.  If I go to that URL in the browser, the Hub3 instantly crashes and I get the error "Your ISP's DHCP does not function correctly" in the ASUS dashboard.  After the hub restarts, usually I can go to that page fine, and everything works as normal.

Where it gets weird - it only seems to fail on Tues, Wed and Thurs.  On Mon and Fri it hasn't failed yet (probably jinxing it now) -- but the issue has been happening for weeks and never seems to be an issue Mon or Fri. 

Then today the behaviour changed again -- after the Hub restarted it still wouldn't work at all.  I went to the page and the Hub crashed 4 times in a row.  I left it alone for 30 mins, tried again, and back to working.  Which I don't understand.

I had a Virgin engineer in a week or so ago, and he couldn't figure it out.  He swapped the Hub3 for another one just in case, but while we were experimenting we confirmed that it's only when the Asus router connects to that URL that the problem occurs. After that I went searching on these forums and came across a few similar issues (for example: https://community.virginmedia.com/t5/Networking-and-WiFi/SH3-modem-mode-no-internet-to-ASUS-RT-AC86U... - I tried switch the ASUS DHCP to Continuous mode as suggested, and the problem seemed to go away for a few days, but then came back again).

Today's issue is more worrying (where 3 to 4 restarts didn't fix) because it seems like it's getting worse without me making any changes...

Anyone have any suggestions?

[legacy1]

Connect the PC to the hub in modem mode (turn off hub for 2mins then on) when you have internet go to that URL.

Its possible the ASUS or firmware when handling DNS don't like that URL and causes the WAN link to reset.

You can also try setting DNS on the PC to use 1.1.1.1, 8.8.8.8 or 9.9.9.9.

[jrb2021]

I don't think it's the WAN link resetting.  The hub is definitely crashing (lights flash on the front, and the phone goes out until it restarts).  When the virgin engineer was here we connected directly to the hub after it restarted and tried a few connections and it was fine.  It's something the ASUS is doing which causes the hub to crash (why for that one URL is a complete mystery to me).

Good idea on setting the DNS on my PC.  I'll give that a whirl.

Thanks!

[jrb2021]

Touch wood, but setting the DNS in Windows to google (8.8.8.8)  appears to helped.  I'm on day 2 without a hub crash after making that change. 

[Andrew-G]

If you're using Google's otherwise excellent DNS, you're handing their advertising algorithym all your browsing on a plate.  Whilst no DNS is guaranteed proof to snatching that, Cloudflare or OpenDNS might be a better bet if you don't want to make things to easy for the online ad-spewers.n  All my devices use Cloudflare, and I've found it fast and highly reliable (more so than a certain ISP's own DNS, for a start).

[jka94036]

This is interesting as I have the same router. Is is best to set the ASUS Router WAN config to Cloudflare DNS rather than the default setting or each device ?

[Tudor]

I use Cloudflare DNS with my 2 x Pi-hole DNS servers and have found it excellent. Do some searches as they also offer childsafe/websafe type functions on some of their DNS servers.

[jrb2021]

Unfortunately on day 3 it failed again. Seems like it's nothing to do with the DNS setting.  Something about that particular URL just crashes the hub.  Today it took an hour to get it to work.  Router crash, wait for it to restart, open browser, try to connect, crash, rinse and repeat.

This seems like a fundamental flaw with the virgin hub doesn't it?  I can't see why going to a particular URL would cause such a fundamental system crash without this being just a bug in the system.

[lotharmat]

What's the URL? (if you're willing to give it)

[jrb2021]

I sent via private message, because I don't know who to ask permission from at work to post an "internal" remote access url on a public forum...