While always true, feline asthma is something a lot of vets handle vastly different. So, hearing about how other people roll with it can have a great benefit (given you do not simply change medications by yourself, but propose other plans to your vet!)
Just a wild guess: are you using the 5ghz or 2.4ghz Wifi? 5ghz is way faster but very fidgety with larger distance to the router, walls in the way or other routers nearby.
So, maybe you can troubleshoot your way out:
Good luck!