can't find my router name (wifi) after android M

Hello everyone , I have received the android m update yesterday and after update has finished my nexus 6 is not finding my wifi . the network is working good on my htc one m8 but the nexus 6 doesn't find that network. even I can see my neighbors wifi on my nexus 6.
can somone please help me :( :(
* I factory rest my nexus 6 and the router but still have the problem