Router resets itself whenever my someone leaves the router range.

So has anyone expereince this issue before? 

Whenever someone leaves my house and the premises or whatever range the router is, the router just decides to reset itself.

I don't know why it does this and its getting irritating when I'm in a game or listening to music and the internet resets. 

The 2.4GHz works fine right after, but the 5G is what takes forever to load back.

And its ALWAYS whenever smoeone leaves. I can't find in any of the options that would cause this to do so. 

Please advise.