Hi,
I am facing the same issue -- updated foolishly to the iOS18 beta on iPhone XS (while abroad) and could not connect to the cellular network at all! miserable a nd stressed me out since i am not home!
I am still working with Apple tech and sent them all of the details they requested but i think i have a temp fix.
IOs18 is messing up connectivity with 5G so when you switch manually to 4G network - it connects fine and everything works --c alls, texts, data without wifi.
How do you switch to 4G manually?
Go to settings -- general> select your cell sim line > turn it on >network selection -- turn off the automatic selection toggle and manually select whichever 4G option is available in your area.
make sure your data roaming is also on along with your cellular data option pointing to the right active line,
Also, what I did last two days (not sure at this point all that was needed! ) but maybe:
1. I erased my phone completely AFTER making an iCloud backup of everything.
2. Restored the IOS using my mac -- does not take too long with wifi
3. Set up my iphone as new -- this is imp if you want to avoid downloading any software glitches that may have been previously.
4. backed up my data using my Icloud -- this took a long time for me given the photos/texts/emails etc.
Hope this helps others!
