tailscale: Unable to resolve dns on Android 13

I have this same issue, have to stop and restart Tailscale to resolve. The issue seems to only happen occasionally when moving between networks, but not always. Most commonly I notice it when I’ve left my home wifi and then attempt to connect to the Internet from mobile networks like LTE.

Thanks for replying!

One way to work around the issue would be to set “Override local DNS” in login.tailscale.com/admin/dns

Enabling “Override local DNS” does fix the DNS issue for my Android device, but it would also override the DNS setting for other devices. Is it possible to enable this setting for one specific device instead of a whole tailnet?

The tailnet in its https://login.tailscale.com/admin/dns has “Override local DNS” turned off, which means Tailscale is supposed to find the DNS servers which were already present in the underlying OS and use those.

Android makes this difficult: starting in Android 8, apps are not allowed to retrieve the DNS server properties like net.dns1 or net.dns4. We instead implement a series of mechanisms in https://github.com/tailscale/tailscale-android/blob/main/android/src/main/java/com/tailscale/ipn/DnsConfig.java

Shortly before the bugreport while on mobile data, all of those mechanisms fail to find a DNS server:

2023-04-30 00:49:24.449414758 +0000 UTC: getDnsConfigFromLinkProperties:
2023-04-30 00:49:24.45033053 +0000 UTC: getDnsServersFromSystemProperties:
2023-04-30 00:49:24.4510717 +0000 UTC: getDnsServersFromNetworkInfo:

Earlier, on Wi-fi, it did find the DNS servers in use:

2023-04-29 16:43:19.169134333 +0000 UTC: getDnsConfigFromLinkProperties: 192.168.x.1
2023-04-29 16:43:19.169683731 +0000 UTC: getDnsServersFromSystemProperties:
2023-04-29 16:43:19.171425349 +0000 UTC: getDnsServersFromNetworkInfo: 192.168.x.1

One way to work around the issue would be to set “Override local DNS” in https://login.tailscale.com/admin/dns

I found some new info:

If I switched to wifi before enabling Tailscale, DNS works.

If I use mobile data before enabling Tailscale, DNS is broken.