dhclient errors cause network to go down

[scopecat]

After upgrading to 26.1.1, I had an issue where connectivity would drop a few hours after my router's boot. I reverted to 25.7. I recently tried again to upgrade to 26.1.2 and encountered the same issue. I looked in the logs and found this section of dhclient that I think is relevant. I've downgraded again to 25.7 and am no longer experiencing this issue. Can anybody help me troubleshoot?

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2026-02-14T21:01:20 Notice dhclient dhclient-script: Reason PREINIT on vlan01.0.201 executing
2026-02-14T21:01:20 Notice dhclient dhclient-script: Reason EXPIRE on vlan01.0.201 executing
2026-02-14T21:01:07 Error dhclient send_packet: No buffer space available
2026-02-14T21:00:48 Error dhclient send_packet: No buffer space available
(Bigger log attached)

Thanks!

[scopecat]

I narrowed it down to Unbound. Restarting the unbound service fixes the issue.

In trying to diagnose this issue further, I ran into the following error message:

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[1779057884] unbound[8483:0] warning: setsockopt(..., SO_SNDBUF, ...) was not granted: No buffer space available
[1779057884] unbound[8483:0] warning: so-sndbuf 4194304 was not granted. Got 57344. To fix: start with root permissions(linux) or sysctl bigger net.core.wmem_max(linux) or kern.ipc.maxsockbuf(bsd) values. or set so-sndbuf: 0 (use system value).
Setting kern.ipc.maxsockbuf=8388608 seems to fix the failure. Does anyone know why unbound is asking for more buffer space than OPNSense is configured by default to give?

[nero355]

Setting kern.ipc.maxsockbuf=8388608 seems to fix the failure.

What was the default value ?!

Does anyone know why unbound is asking for more buffer space than OPNSense is configured by default to give?

It looks like this issue : https://docs.pi-hole.net/guides/dns/unbound/#fix-so-rcvbuf-warning-in-unbound

What is the size of your network ?
How many Clients ?