Hi all, I’m using an Air 3S with the DJI Cellular Dongle 2 (Enhanced Transmission), and it works perfectly with the DJI RC 2. But after switching to the DJI RC Pro 2, the 4G connection doesn’t show up at all. Has anyone managed to get this working or found any workaround?
Check the firmware of both, more info here 
It won’t work, you need the even newer dongle, I will find the link, and sadly by the looks of it you will need 2, one for the RC Pro 2 and one for the Mavic 4 Pro and again sadly they are not legal in the UK and DJI very much doubts they will be, the powers that be the CAA have decided they are too dangerous and will allow flyers to be able to fly too far and not adhere to VLOS
edit, just reread you have the Air 3S, I am sure the Dongle 2 will work with the one below, so you wil only need one, but again there is no guarantee that it will work
Didn’t I read somewhere you also have to hold an Ofcom UAS Operator Radio Licence to use such equipment.
Oh yes you need a special radio licence, too many hoops sadly