Since the update to Android 11, a weird issue came up: when using the wifi hotspot functionality, DNS resolution is broken for some devices which connect to the internet via the phone.
Specifically: I run an Ubuntu 20.04 VM using VirtualBox on a windows laptop. The windows laptop works fine, i.e. it connects to the internet, my different vpn connections all work, etc.
On the other hand, the ubuntu vm has a problem doing dns resolution. It has a "NAT" network connection, using IntelPro1000/MT virtual NIC, with the cable-connected flag enabled. Virtualbox version is the latest: 6.1.18.
What seems to be happening is that the systemd daemon, handling the dns resolution in ubuntu, gets the IP of the phone as DNS server (correctly, I presume, as windows also has the same IP for the dns server). But then it has problems communicating with it.
The syslog file presents many messages similar to the following:
Apr 11 07:48:46 ubuntu20 systemd-resolved: Using degraded feature set (UDP) for DNS server 192.168.21.8.
In case anyone else has the same problem: I somehow managed to fix this. I am not 100% sure about what did it, but I have:
- wiped app cache (and restarted the phone in the process)
- changed network config for the phone wifi hotspot to use 5ghz instead of 2.4 ghz
- changed network config for the phone wifi hotspot to use Protected Management Frames
Sadly it seems that the solution was only temporary, and most likely not due to the config changes described above. Today the same issue started happening again 😞
I tend to rule out problems with the VM itself, as it had been working fine for a long time, and it did not have recent package updates involving core networking functionality
Yesterday I installed the new OS update made available for the A40. It sadly did not fix the problem.
The workaround I put in place in the end is to set systemd-resolved to use the Google DNS servers, by editing /etc/systemd/resolved.conf