What are the Best Router security settings?

My devices seem to go offline for a second or two multiple times a day.
Shortest doesn’t even give a time statement, most are under 2 seconds but some can be 3 minutes.

If there was a pattern of the timeframes, I would think coding was the issue, but some days it might be 10 times other days it could be 500 times a day. So I’m thinking it might be my router settings
I have devices in 4 different environments.
Using different brands of routers, TrenDent, a Cisco, and a Linksys, along with a T-Mobile cellular home internet device, this one has the least of offline notices.