A number of us users have spent hours trying to figure out why our iPads don't show up in the All Surfaces list in EuControl, only to find that it all works fine if we install a different router. No known settings are able to solve it. No list of compatible routers is known to exist. It currently comes down to luck whether you happen to have compatible wifi. Please test it with a wider variety and make it more compatible.
In my case, it was quick and simple to get it working at home with my AT&T U-verse router. But no combination of settings will get it working at my company's main studio with a Cisco wireless router. I am connecting at 5G, and the router works flawlessly for all other tasks.