Giga Hub 2.0 - Android phones connected to the regular network display "no data connection"

[msh]

Android phones connected to the regular network often display "no data connection" or "no internet connection" and unable to resolve DNS, when connected to the guest network - working fine

[msh]

The same problem occurs with a Chromebook. As a workaround, switching DNS to Google or Cloudflare, instead of the one advertised via DHCP, solves the issue

[msh · Accepted solution]

The problem disappeared for now after a couple of modem reboots.

[Vanadiel]

Should this happen again, try a ping or traceroute from an affected device to 8.8.8.8.

It's possible you somehow lost DNS resolvement rather than loosing connectivity.

[msh]

This doesn't make any sense, sorry. If you want to verify whether the server is able to resolve, you need to use nslookup or dig, or a similar tool, but I fail to see how this is relevant, as this is not a Bell server and not typically used by the modem.

I understand very well what happened - the modem runs an internal DNS server, and it stopped working properly on the main subnet. I verified that DHCP advertised the correct one - the modem, and I tried to replace upstream servers, which didn't help.  Setting nameservers to Cloudflare / Google just bypasses the modem server. After reboot, it was working again with the default Bell upstream DNS servers. I guess just one more bug of Giga Hub 2.0

[Vanadiel]

The modem does not run a DNS server. It simply provides the IP of a DNS server as part of the DHCP information passed on to the end devices.  You can change it to use for example 1.1.1.1 or 8.8.8.8 as alternative to the default Bell provided configuration.

Devices like phones typically check a known web address to verify internet connectivity. They will display "no internet connection" if they cannot reach the address. To reach it they need working DNS.

That is why I think, based on your original post, that you are actually not loosing your internet connection but rather the ability to resolve addresses using DNS.

This can have multiple causes, but checking if you can reach 8.8.8.8 will rule out any other issue like a temporary network failure on Bell's side etc...

[msh]

Of course it does, run wireshark and dump DHCP ACK - option 6 contains the address of the modem, which is the first advertised nameserver. I stated it right in my first post in this thread that the problem is DNS resolving, not connectivity.