I can't log into minecraft over my local network.

I can't log into minecraft. Neither using the Minecraft launcher nor over the website.

The launcher says that my login information is wrong but if i disable wlan on my handy and try to log into the website using mobile data everything works fine. The problem occurs only if i or my brother try to connect over our local network. I just played yesterday. And i already tried to restart the router , checked my hosts file, nothing worked.

 

So its either a problem with our internet provider or our ip-range got falsely flagged or something like that.