You can check if the transmit power is set to 100%.
Is there a wall between your router and device?
5G will loss more signal than 2.4G when cross a wall.

Yes Transmit Power is set to HIGH.
Yes, there is a regular wall but with door. But I thought that is what Archer D9 is promoting beamforming and advertising wider wifi range, which makes the device highly priced (4x times) than regular routers.

i agree

Please forgive me all. I don't mean to hijack this post, I just can't seem to create my own. I got to Home section, then Wireless Router and I get "Sorry! This forum is not accepting new posts."

Can anybody point me in the right direction? I have an Archer C7, but when I connect my ftp server to the network, it is only reachable from outside the LAN if I connect to the 5 ghz band--that keeps dropping. I need to be able to connect it to the 2.4 band, while still reaching it from outside the network, because that one stays consistent.

Again, I am very sorry, and thank you very much.