yup, I had this issue. I restarted my home hub and it worked fine. I’m not an IT expert but possibly because it is a split system. i.e 2.4 and 5ghz, maybe they just aren’t on the same wi-fi. You used to be able to split the channels which worked great. So just force close your companion app. Turn hub off and on. Then connect to zwift and open companion app. Sometimes takes quite a while to connect. Sometimes takes a while if i switch between PC and ATV. I regularly switch the hub on and off which seems to avoid issues.
Just incase any stumbles across this with a similar setup i thought i would post my recent fix
I have one of the whole home discs in the garage where my pc and zwift setup is
The pc was a 2.4 ghz connection via a wifi dongle, after connect the pc via an ethernet cable to the disc it now communicates with the iphone alot better and i seem to have better app performance.
Im assuming a 2.4 and a 5ghz combo just doesnt work to well on the whole home setup
Maybe a 5ghz wifi dongle would have worked but for now a cable will do