I have tried to open minecraft realms with 1.9.1 but it wont work for me.
I tried it with 1.9 and it also didn't work.
I tried re-opening minecraft 4 times.

UPDATE
Mojang fixed it in 1.9.2, if your friends are having troubles joining realms just close realms and then open it again! I had to do that for my friend. Thanks for everyone who helped!