Issue Custom port for Plesk seems to be not reachable anymore by external services after latest upgrade

[King555]

Server operating system version

Ubuntu 18.04.6 LTS x64

Plesk version and microupdate number

18.0.56 Update #1 web admin edition

I use a custom port for Plesk (something like 12345) and upgraded from Plesk Obsidian 18.0.52 Update 3 to 18.0.56 Update 1 and now I have two problems, which were not there before the upgrade.

1. The Plesk mobile app (Android) does not fully work anymore. While the first page in the app still works (seems to be just a web browser), the other 4 pages don't work anymore. I had this problem a long time (see Resolved - Three functions not working in Plesk mobile app), but it worked since March 2023.

2. The site uptimerobot.com, which monitors several websites and ports on my server, says my Plesk port is not reachable anymore. I already deleted and re-created the monitor there, still not reachable.

Since these two problems occured at the same time, they might by related. What could be the reason? Any ideas? Of course Plesk is still reachable via browser, and only via the custom port.

EDIT: I almost forgot: The monitoring of the Plesk web server via the Watchdog extension never worked (maybe because of the custom port), but currently it works (since the update). That's the third thing which changed after the update, and everything seems to be port related.

 

[King555]

Strange thing: After the last update I could not connect to Plesk anymore, because the ports were reset in the corresponding config files (Resolved - Can't connect to Plesk after update to 18.0.61 Update 1). Now that I changed the ports in the files back to my values, the mobile app (see 1.) and the external monitoring site (see 2.) work again, monitoring of Plesk via Watchdog (see EDIT) does not work anymore. I really do not understand what's going on here, why one time one thing is working and one time another thing.