Why won't my android tablet go online?

[KittyLovesPaintingOhYes]

So, I've had a 2015 nexus 7 for a while, everything ok, now all of a sudden it won't connect to the internet. Wifi is fine, I've gone through the techy sites and followed every tip I could understand and all that works is:
'Forget' IP address
Reboot router
Re-enter IP address

...and we're off, but only for about 30 minutes then it's back to square one, and if I have to stare at that little exclamation mark next to the wifi symbol any more I'm going to go mad.

So, do I now just have a glorified coaster? I only use it for internet stuff and it was given to me second-hand so no help there.

Have you tried setting your IP address to static rather than dynamic?

Thanks Lougle, I'm not sure how to do that, I'll have to look it up in the morning. I'm just baffled by why a perfectly functional piece of kit suddenly gets internet-shy when I've been using it for months and nothing else has changed.

Off to bed now, worn myself out shouting at it (that didn't work either...)

Is it a factor of distance? By that I mean if you sit in the same room as the router does it still drop out?