Won't stay connected to wifi

[jackal24]

Whenever I put my phone in standby for a while it disconnects from wifi and will not reconnect until I go into wifi and select the ap. This happens 2 different ap's (one unifi and one linksys) that both have strong signals and work five with everything else.
I have tried both settings on "switch to mobile data" and have tried "forget this network" and reconnecting.

 

[Rukbat]

See if there's a "do not turn off when on lock screen" choice or something like that. That function's been causing problems on many Samsung phones for years.

 

[jackal24]

Don't see any setting like that

See if there's a "do not turn off when on lock screen" choice or something like that. That function's been causing problems on many Samsung phones for years.