@MrMuse:
I have a Dedicated Computer Aliased for all my Torrent Activity
which I leave on all the time.
I do ReBoot occasionally for maintenance.
What I find is usually the same port retains,
presuming the VPN Connection Location is the same.
Upon ReStarting the Computer,
after PIA ReConnects I check if the Port is the same.
When it does change (rarely),
I simply make the change in my Router prior to Starting qBitttorent,
the after starting qBittorrent,
make the change there.
;r
p.s.
I have had to leave the Computer off for hours (4-12) for various reasons,
more times than not the port has remained the same,
again presuming the VPN Connection Location is the same.