HELP GS110EMX low Upload Speed when connecting at 2.5Gbps on ports 9 and 10

As you experience the same with the RAX200 as well as we th the probably very similar Asus consumer router in AP mode, the idea is near that we're facing yet another well hidden performance issue operating such devices in AP mode, well possibly caused by some chip and platform maker implementation issue. Not the first we're reading about on various manufacturers communities. >99.9% of the implementation, testing and marketing money does flow into shiny consumer and influencer channels. Nobody really cares much about AP modes, especially if paired with exotic multi-gig technology. My advise: Stick with true SMB class access points like the WAX6xx series, stay far away from consumer routers for these purposes.