HELP! fetch: stuck forever OR error: RPC failed: curl 56 recv failure: Operation timed out

From: FreeBSD User <freebsd_at_walstatt-de.de>
Date: Tue, 03 Dec 2024 19:46:09 UTC
On most recent CURRENT (on some boxes of ours, not all) fetch/git seem to be stuck
forever fetching tarballs from ports, fetching Emails via claws-mail (TLS), opening
websites via librewolf and firefox or pulling repositories via git.

CURRENT: FreeBSD 15.0-CURRENT #1 main-n273978-b5a8abe9502e: Mon Dec  2 23:11:07 CET 2024
amd64

When performing "git pull" und /usr/ports, I received after roughly 5-7 minutes:

error: RPC failed: curl 56 recv failure: Operation timed out

Ab initio cloning isn't possible, I had to rsync, but after that, for some hosts pulling
ports or /usr/src worked again.

Conneting to my Email provider via claws-mail results in logon failures, opening websites
via librewolf/firefox (youtube, i.e.) results in a stuck connection - I have to open the
site repeatedly to open it by chance.

I'm out of ideas and this drives me nuts! In the lab I updated today several other hosts
to most recent CURRENT and those machines do not show this strange behaviour, but they
open and pull sources via "git -C /usr/src pull" somehow slow (it take a while until  the
connection opens).
The only thing in common of those boxes in question is an older Intel NIC, em(8) based.

I can not pinpoint the problem, it occured 1st of December.

Sorry for the fuzzy description of the problem, I might be of use of some hints how to
investigate more deeper

Kind regards and thanks in advance

Oliver