I can't get on Minecraft Server?

I bought the Minecraft Java Edition so I can play with my friends. In the first two weeks everything was normal, but then I always had to restart my PC to get on the server, and now I can't figure it out anymore. It always says: "Connection failed" "Registration failed: The registration servers are currently shut down for maintenance." But it works for my friends: /

According to the message, the servers seem to have just been shut down due to maintenance. Your friends come to the server. Ask once if they can restart the server or if you have been whitelisted.

"But it works with my friends" is the question.

Restarting and whitelisting won't help, the problem is with his computer / firewall.

Does it work if you turn off Windows Firewall?