@Kevin_Z unfortunately the unit is all packaged up with postage and is being RMA'd and I'm going to send it back on monday 9/28. Basically it's exactly as explained (firmware version, etc) above. Neither of the 5ghz bands are available they are greyed out in the wireless settings section with the message that they are not available in my region or country. However the guest 5ghz wireless is not greyed out and they do work. However I want full functionality, i.e. i want to be able to get to the admin UI while being connected to 5ghz over wireless and afaict that's not possible on a guest network.

@Kevin_Z I upgraded it by clicking upgrade through the ui where it downloads and upgrades automatically, I'm guessing it's the same as this one Archer A20(US)_V1_191026 from the main download page https://www.tp-link.com/us/support/download/archer-a20/v1/#Firmware. Not being able to downgrade firmware is also annoying. Tried with the Archer A20(US)_V1_181122 file from the same page and it wouldn't take it, giving a simple "upgrade failed" message (or a very similar short message) almost immediately. Tried both over wireless and wired connections with the same results.

@Kevin_Z hah, no i mean it's being RMA'd to tp-link. going to the post office in a few hours