Thanks for the info. That makes sense given the "11s" configuration I found for those SSIDs. The router is not in their mesh line AFAIK, though most of their home products now support OneMesh, so that line is a bit blurry.
To clarify, I like TP-Link products too. Their PowerLAN products so far have been the most reliable for me and the router's been solid too. It's just really disappointing that an almost (for me) perfect product has this very simple software flaw without any solution other than to hope the manufacturer decides to fix it at some point. I had the same issue with Asus routers, but they were smart enough to open source their software and let others fix pretty much everything for them.