Firewall is blocking WinSCP?

Hey there,
I know that there is a seperate article about this, but the tipps didnt helped me or fixed my error.

I wanted to connect to my server, but I got
Network error: Connection timed out
So I followed the tipps listed here: https://winscp.net/eng/docs/message_connection_refused

Yesterday everything worked fine, so I thought it should be the firewall.
I tried everything but winscp was enabled evrywhere, so I thought my router was the problem. I disabled the router firewall and my pc's firewall but it didnt fixed the problem.

So I opened a wifi hotspot with my mobile phone and voila: it worked.
I didnt changed anything in the settings, only my wifi.

I would be really happy if someone can help me, the wifi hotspot is a imperfect solution.
Thank you.

If it stopped working suddenly, I would not expect the problem to be the firewall. It's rather something on the network.
Can you connect with any other client using the same protocol?