As of today, my friends and I have had trouble joining/connecting to each other's worlds. I play on Windows 10 edition and frequently play with these friends who play on Xbox, Pocket Edition and Nintendo Switch. On my world we had been preparing for the Ender Dragon (all 5 of us in-game) when I had to restart due to my PC overheating (This is a common issue with me and has never affected Minecraft). When I got back, the first of my friends to join was my sister, who was on Pocket Edition and in the same room (so she connected through LAN) and then the rest of my friends not using LAN to connect could not. They were stuck on the loading page after using invites and the Friends page. We ended up getting 4 of us on at once but couldn't get our Nintendo Switch friend on at all. We gave up after an hour of connecting and disconnecting. 

This is unlikely to be an issue with my WiFi as it is stable and reliable. I tried later to join one of my friend's worlds and it was doing the same to me.