[Networkmanager] dns-mgr occasionally writes resolv.conf in the wrong order

[Beniamino Galvani]

On Sat, Jun 24, 2023 at 03:30:32PM +0200, Bjørn Mork wrote:
> Sometimes I end up with a resolv.conf in the wrong order wrt routing
> defaults.  The DNS servers listed first do not belong to the ISP
> providing the default route.
> 
> This causes severe DNS timeout isues because those servers either are
> unreachable or refuse recursive queries over the default route.
> 
> I believe the problem started when I went from the Debian bullseye to
> the Debian bookwork version of NetworkManager. I.e from 1.30.6 to
> 1.42.4, but with some Debian patches if relevant.  I've been trying to
> reproduce it for a while, without being able to force it.  So I'm not
> exactly sure what the trigger is.

> [...]

> I don't exactly understand what this means, but it looks like
> NetworkManager considers all 8 DNS servers equal ("best")?  With both
> links having "priority=100, default-route=1".
> 
> This does not reflect the actual priority, as shown above, where the
> wlan0 (ifindex=3) link has a lowe metric than the wwan0 (ifindex=29)
> link.
> 
> Anyone have a clue why this happens?

Hi,

please try a more recent minor release from the 1.42 series if you
can. I suspect this patch could fix your problem:

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/commit/0a02995175e06e62924705393121a1c5efc3822d?merge_request_iid=1583

If not please file an issue on gitlab and attach a complete trace log
since the startup of the daemon.

Thanks,
Beniamino
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