An existing connection was closed by the remote host? - 1

I recently got this error message after 5 minutes on my Minecraft server. So I'm kicked! I've already read through a bit and with the firewall I'm not sure if something is wrong:

That really annoys me because I can only max. 5-10 minutes on my server, then I will be kicked again! I have often restarted routers!

I hope someone can help, and if you please explain to me in detail because I'm not very familiar with the firewall, thank you.

Are you entering the server on your PC or have you rented it somewhere?

Rented from MC-Host24. But it was always great. Only since yesterday this error

Yes, that happens sometimes - when the internet line spills around at home. Sometimes it was like that for me, I couldn't do anything. Alternatively, look in the logs from the server?