Solved - Google Nest Routers don't allow you to select the channel. AX1800 Access Points don't allow you to select SSIDs in the "5G-2" channels (in the network tools part of the Omada app you can see...

I've purchased an AX1800 Access Point as an outdoor access point, to extend the range of the Google Nest Router (mesh wifi) in my home to the outdoor area. The range is great, no issues there. But...