@ccadar 

Hi,

Is this with "Smart Connect" enabled or disabled?

Are you using different Network Names (SSID) for 2.4 GHz and 5 GHz or identical names?

  @woozle 

- smart connect is disabled. I use an outdoor camera to connect to its 2Ghz Wifi Network 

- they have different SSID names.

I used to have the same laptop connected to a tplink ax1800 router but there everythng works just fine..

  @ccadar 

Given that TP-Link has probably sold thousands (if not already tens of thousands) of Archer C80 worldwide and your particullar problem is not a hot topic in this forum, we should assume that this is not a general problem of this router model.

When this problem happens can you test if the Windows laptop is still able to access the Internet when connected via Ethernet cable to one of the LAN ports of the C80?

Furthermore, if you don't mind the effort of configuring the C80 again you could try if a Factory Defaults Restore might make any difference. 

If you do, then don't make too many settings changes at once. Maybe just configure the PPPoE connection and wireless 2.4 GHz and 5 GHz and then check if the problem persists.