Trying to connect my Brothers two Play 3 speakers, go through the process and it says they are connected but when you reopen the app they are not there.

i have taken the Play 3’s to my place and they work fine and are up to date.

take them to his place, factory reset them and it goes through the process but they do not appear.

i have scanned the network and they are connected to WiFi.

so I suspect the router, he has an Archer 1600 which is a common router.

it was all working fine on S2 app

my question is, are there any specific settings in the Archer router that need to be on or off to be able for it to work.

this one has me stumped 

thanks in advance