Manually select all the available check-boxes next to each speaker/room in the room grouping screen in the App and see if that fixes it.

Hey, 

yeah tried that won’t work. Nothing happens. But all are connected and online, and I can play group 3 different in the living room and play something there, but the one in the bathroom don’t want to group with the rest, and I can play only separate music there

In that case, perhaps screen-capture your issue with a video recording (showing you trying to manually select each one of the Sonos room check-boxes) and post a link to it here with a system diagnostic report taken shortly afterwards. Post the reference here too and then speak with Sonos Support via this LINK

Ensure you are selecting the ‘check boxes’ as shown in this short animation attached.

Thanx for the video,  but I know how to use the grouping. And it has worked before. It’s just suddenly now it won’t work at all.

Perhaps contact Sonos Support as mentioned in my earlier post - the link to their contact page is in that same post too… hope you get it sorted.

Have you tried a system refresh?:

Power off all Sonos, restart the router and wait until the router has fully restarted, before you power on Sonos.

Hey, Thanx. I will try out that

If the refresh works, consider assigning static/reserved IP addresses to your Sonos using the router’s DHCP page. It helps stability for a lot of folks.

hey.. Hmm How do i do that?