Issue Docker proxy timeout with firewall enabled

[koentjev]

Hi guys and girls at Plesk,

After adding a new docker container yesterday all my docker proxies stopped working.
I've been investigating and just now found out that when I disable the Plesk firewall everything comes back up.
When re-enabling the firewall proxies stop functioning again, resolving in gateway timeouts.

Does Docker write firewall rules? Or do you guys have other ideas what could be the reason for this behaviour?

Regards
Koen