Just revisiting this to get some closure. I ordered a Pi5 8G and started with a fresh 12.2 install thinking it might help, but still having the same 'invalid key' problem. Since they're inexpensive, I'll give an external antenna a go. Would you say this is acceptable or is there another model you'd recommend?
https://www.amazon.com/gp/product/B01GC8XH0S/ref=ox_sc_act_title_1?smid=A2JTFL4V8HYESG&psc=1