During IPFire boot, I see the following after the “Starting DHCPCD on the red0 interface” Message.
"RTNETLINK answers: no such file or directory"

it may later be followed by
"Error resolving 0.ipfire.pool.ntp.org: name or service not known (-2)

Looking at prior Topics, it is suggested that this RTNETLINK message should be ignored.
This just started today Aug 9, 2021 and shows on both core 157 & core 158 PCs.

See the answer by @arne_f in the following post:-

This may have some relationship to this post from @pmueller
Are your DNS server selections all working well on the DNS page?