I have another issue with the SDIO module. I am using it only with 2.4ghz. If I use a device and browse with it it is incredibly slow. Web sites need up to 10 seconds to load. Other routers with 2.4ghz aren’t that slow.
If I check the RX / Tx Rates in luci These are really low (1mbit) despite reasonable signal strength (-67dbm) and noise (-78 dbm).