tintedvision

I am experiencing the same issue. Try continually booting the system every 5 minutes for a total of 60 minutes and report back.

if you have the issue on wired connections too then it's probably the modem/router combo. another thing to try is to put it in bridge mode & connect a device wired to see if it experiences the issue. other than that it would likely be an ISP issue, either with the lines to your apartment or in your apartment. You need to keep on them about it, i know it's frustrating but they will always brush you off if you let them. ISPs are pretty bad for that.

When I had this issue on cable it was because one of the coax cables was bad off of the splitter.  I had a tech come and he found the issue when testing the lines.

His current box has the fiber connected directly to it. So how is he going to hook fiber up to the Archer C7?
 
Here is a PDF Manuel on what the OP has: http://www.kustbandet.com/LinkClick.aspx?fileticket=fpVNFrjxjEY%3D&tabid=117&mid=487

The TP-Link Archer C7 is a pretty solid router and should fall within the budget.

Good point, I keep forgetting it's a combo unit.

Yeah I see where you're coming from. I'm calling them now and asking for a replacement.

just a note ahead of time: no one is gonna die if you dont have stabile internet, this isnt urgent. (actually one of the ways we decide urgency of tickets at work..)
 
few more things that would come in handy to know:
- where did you move from (general area/town/city is enough)
- where did you move to (same as before)
- which ISP did you come from, and which did you move to?
 
(seeing from your speedtests you're danish, i'm hoping some danes can chime in on the ISP side of things)

Definitely sounds like a bad router portion of the unit.
Hopefully you can get them to not hang up on you when you call and see if they'll send another unit out.