Not all wireless clients have the ability to detect 5GHz signal. What's the device? You can google whether it supports 5GHz. If it does support 5GHz but not see it, make sure the 5GHz wifi light is...

The NC220 use port 8080 and 80. Did you guys open the right ports for the camera? You may check the ports forwarding using Lan IP:8080 internally and wan IP:8080 to access to the camera externally....

Can you share us the error code 502's screenshot? The settings you typed in maybe not correct. You can contact TP-Link support for further analyze.

What are the 5 fixed IP? Do they include IP address, Subnet Mask and Default Gateway? You can change the WAN connection type to static IP in this case. If they are in the same IP range, I'm afraid...

The Basci- Status part has wireless and wired clients showing separately. Actually the Access Control parts will show the device connecting wireless or wired .

Hi Alan. That‘s because you were updating the same firmware as the current firmware version. Your C20 already has the latest firmware version.