Android phone won't download when both wifi and data on. whats the problem?

samsung galaxy s7.

tried resetting modem/router. about to try changing the channel.

when i turned data off, it worked on wifi
Update: have re started the phone
Update 2: tried changing channel...won't save settings
Update 3: my weather app is also affected
Update 4: i have 2.4 and 5ghz..tried turning 1 off, it wouldn't turn off
Update 5: it started working in the middle of the night and updated all my apps....
Update 6: changing the channel on the router has reconnected my ereader as well as my friends laptop at his house....when other devices weren't working, but 1 wouldn't.
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