(X)ubuntu 20.04: GUFW and MS-Teams slow down traffic intermittently

[Christoph W]

Thanks for Gufw!

inxi -S output: Xubuntu standard LTS installation - Kernel: 5.4.0-77-generic x86_64 bits: 64 Desktop: Xfce 4.14.2 Distro: Ubuntu 20.04.2 LTS (Focal Fossa). GUFW 20.04.1, MS Teams 1.4.00.13653 (64-Bit) (all up to date at the time of this report).

** Problem: 250 Mbit LAN connection slowing down *intermittently*, but reproducible, to a crawl of 300 kbit or less if Gufw is activated parallel to MS teams.
* Gufw is used with only basic settings provided after installation (in:denied/out:allowed and nothing else set, no further rules).
* There has not to be any active call in teams, just running it seems to cause the problem after a while (<5 minutes).
* After congestion for some time (minutes), the system may recover to full speed again, only to succumb again after a few minutes.
* Other parallel running programs' connections are slowed down as well in accordance, e.g. parallel samba file sharing download is affected as well.
* Stopping teams restores the connection speed after a short while (~1 minute).
* Parallel connections to the LAN(router) are not inhibited, it is just the one computer.

Teams seems to switch ports after restarting (UDP6/~34nnn-4nnnn). I set up a range to be allowed within ports used by teams (e.g. 30000:55555, allow in/outbound) to no avail, connections dropped still to low speed.

Thanks and regards,
Christoph

[costales (costales)]

Hi,
Gufw can't affect that behavior. I think is an ufw issue.
Best regards.

[Jamie Strandboge (jdstrand)]

It is unclear from the description that this has anything to do with networking. Are there any firewall denials in the logs (eg, /var/log/ufw.log or /var/log/kern.log)? If you disable ufw (sudo ufw disable) does the problem go away?

As an aside, IIRC, MS-Teams is not a lightweight application and I suspect this could be memory consumption unrelated to the firewall.

[Launchpad Janitor (janitor)]

[Expired for ufw (Ubuntu) because there has been no activity for 60 days.]