Issue Monitoring Plesk port via uptimerobot.com makes trouble since (ca.) version 18.0.65

[King555]

Server operating system version

Ubuntu 18.04.6 LTS x64 (ELS)

Plesk version and microupdate number

Plesk Obsidian 18.0.65 Update #1 Web Admin Edition

Is there anybody here who monitors his Plesk installation via uptimerobot.com? Since the 18.0.65 update, but maybe shortly before that, UptimeRobot constantly tells me that the port is not reachable, then after an hour, a day or so the port is reachable again, and so on. I monitor only the port, not the HTTP(S) site.

Maybe this it totally unrelated to Plesk, but I don't know. It almost never happened before. There was a time when the port was completely unreachable for some time for UptimeRobot (from 10/2023 to 05/2024, initiated and solved by Plesk updates), but the difference now is that it's sometimes reachable.

This monitoring worked from 09/2018 until today except for the timeframe mentioned. The Plesk installation in my browser (same port, of course) works always, I never had a problem and also it works at the moment when I get a notification from UptimeRobot that the port is down.

Any ideas? Is there some kind of protection in Plesk? Or do I have to search the solution on my server's side? UptimeRobot sends me many mails and it's annoying (up, down, up, down). Of course I can disable the mails, but I want to monitor Plesk.

 

[Martin Dias]

Locations and IPs | UptimeRobot

If you get any false positives, there is a strong chance that the IPs used are blocked by your hosting provider. Make sure that you allow-list these IPs!

uptimerobot.com

Check if their IPs are landing in Fail2Ban for example

 

[King555]

None of their IPs are blocked by fail2ban. The firewall (iptables) is static, so that's also not the reason. ModSecurity is just for HTTP, if I'm correct. I think that's all I have installed for protection.

UptimeRobot can monitor everything else on the server without any problems: multiple websites via HTTP, several services via the corresponding ports (for example all mail ports) and also a ping of IPv4 and IPv6 addresses. It's only the Plesk port which makes problems.