I have a C8 and can see the clients okay on my iPad using tether. Can you see the clients if you tap the client symbol or the clients button at the bottom of the tether page? Be sure the tether app is up to date and your C9 is up to date.

I have same problem. Did you find a solution?

@CliffordBarker Same happens to me in Archer C6 with latest firmware (Jan 2020), so guess it's an old unfixed bug in access point mode. It's a pity because it was working right fine before it rebooted due to a power outage.

 

Not even pinging devices work anymore (it's supposed to catch ARP packets to build the table). What I don't understand is why it doesn't show authenticated clients, that's something the AP has to know and it's what you're expecting to see in that list.

 

I tried a workaround, setting router mode but configuring it as access point (disabling DHCP and NAT, using the LAN port, setting LAN IP address manually). I didn't achieve Internet connectivity, don't know exactly why... But anyway, I only got it to recognize the device I was connecting from (the one with the web browser). When I went back to AP mode, empty list again.

@CliffordBarker Out of curiosity, have you set the DHCP Server to Off? I've found that was the bug in my C6, check this thread 

 

While playing with the DHCP Server options, every time I would set it to Off, the list would dissapear next time it was rebooted. However, setting it to Auto would bring the list back.