Your IONBEAM should have came with plastic zip tie braces with adhesive backing. Try using those, along with the magnets. Should solve your issues. Feel free to reference my photos if needed.
I wish they were stronger as well, but I'm getting pretty good results and that really seemed to do the trick. Or maybe you could try velcro, that was gonna be my backup ?
As far as wifi issues, I haven't had any... but I did go the extra mile and assigned it a permanent IP, so I don't know if that helped prevent my controller from dropping out.
Most routers by default auto assign addresses and after they time out they're reissued so maybe that's the hiccup?
Anyways enjoy your crop!