@tabcore See how the DFS channels mechanism works in this introduction. I suspect that's the reason for 5GHz wireless network disappearing in your case.

@RongTuli TL-MR3420 HW v2 is under EOL status - its latest FW release is from 2015 and it's highly unlikely to receive a FW update with the feature in question.

@yxyychw Here's your router user guide. In Chapter 5 you can see how to set it up in WISP operation mode. There's no channel selection because the channel has been determined by the network you're...

@Mbuyiselo Go through this troubleshooting guide. It may help fix your issue.

@tausif239 Here's the same feature request as yours, but an older one - you may find some answers there.

@glhunt Make sure that Random MAC Address is turned off for Windows 10 devices as well. Here's how to do that on iPhone, Android and Windows devices.