Satellite of RBK53 suddenly doesn't connect anymore

So I have a strange issue and tried anything I could think off, but still didn't fix the problem.

I bought the router and 2 satellites in one package 1 year, 11 monts and 8 days ago.

Today, suddenly in the afternoon the satellite of the RBK53 lost connection and burned purple. That happened before and most of the time a simple powercycle is enough to get it working again.

Reset didn't work, it gets from flashing white to blue and into purple again.

So I placed it closer to the router, but that didn't fix it.

I re-synced, didn't work. Re-synced again, gets blue, is pingable and disappears after a minute.

Re-synced another time, comes up but connects only to 2.4ghz and with the IP 192.168.1.250. Stays a few minutes and than looses connection again.

So I reset the satelliet and tried to reconnect. Than the satelliet turns into steady blue, but the router doesn't see the satelliet at all.

To rule out any other component in the netwerk, I booted up the second satellite in the package. This one has not been on for several months as I didn't need it anymore. That one instansly comes online on the same spot as the other one. Updates its firmware, reboots and comes back online and is now runing for a few hours without a problem on the old spot of the defect one. 

But the problem still exists with the first satellite. I contacted the store I bought it from, and they want to send the hole set to the repairshop. I do not agree with that. The set isn't faulty, only the satellite is.  Sending everything to them would endup with me having no internet for weeks. And in current situation where I have to work from home, that is not an option.

Netgear cannot be contacted yet, because of a bank holiday tomorrow and business hours being over. It gave the option to reroute to an english speaking person, so I choose that one. But after saying I'm from the netherlands they hang up without any notice. Even the 2nd time they did the same  (may I say Netgear gives **bleep**ty support by phone??).  So I have to wait till friday morning before I can call back. 

In the mean time, does anyone have any new idea what I can do to fixed things here?

Reset of satellite, re-sync, etc. all does not seem to work. It's ligts stay blue, but the router doesn't see it anymore online. 

Both router and sats are on firmware 2.5.1.8