@Kevin_Z 

By "residence" I mean a hotel-like appartment where WiFi network has a login page. There are no problems with it, it stays logged in, and I can login through the 802N router. My computer does not disconnect from it, but TP-Link does that once an hour.

> What is the current network diagram?

Final device (my computer, phone etc) <[local wireless]= TP-Link router <[public wireless]= WiFi network of the residence (I guess, a mesh of switches and repeaters, I don't have access further than a WiFi SSID). The connection marked red is the one that breaks each 40-50 minutes.

> When the connection cut  off, please click here to check the IP address and gateway with your computer connected to the 802N.

It gives me a local IP (it is the IP in the local network, like 192.168.0.2). Gateway is the router itself, which is, respectively, 192.168.0.1. Connection between computer and router is OK, it is router that disconnects from the second WiFi.

> Try to move the 802N closer to the main router and ensure that firmware is up to date. 

I have no idea where the "main router" is, think of it as of a hotel wifi. Firmware is updated, hardware is intact.

> Besides, you can change some wireless settings to optimize the performance, like wireless channel and channel width.

TP-Link console does not let me change something, because router is in WISP mode, which means it should be on the same channel as the second WiFi. When I change something, it immediately reverts. The router is advertised as WISP-capable, so I guess that a "it's too weak to maintain two connections" wuold not be a good answer.