Connection Bug (Realms, LAN, Servers)

Im using Minecraft Windows 10 Edtion (1.2.5) and cant connect with Servers, via LAN or with Realms. With Minecraft PE (same version) i can connect with those three via Wi-Fi. The Firewall is switched off, but it already doesent connect. My brother has the same problem. It had begun ca. 2 Weeks ago, first i thought it is because the Minecraft Update, but there was a new one and it still doesent works. I thougt, that the big Windowsupdate could also be the problem. Therefore i tried playing on a notebook without the fall creators update for Windows (same Minecraft version) and it worked!

When I connect with Realms ist always says loading resource packs. Later i wantet to Play offline and edit a World, but then there was just a blank Screen (see screenshots). It seams like the game thought the offlineworld is my realm (wtf). When i press Play in the edit menue Minecraft wants to connect with the Realm (doesent works), but when i press Play in the normal play-menue i can connect with the offline world.

I also cant Play via LAN with my brother, and when trying to Play on a server there is just the "connecting to external server" message.