Two weeks ago, I returned to Canada after being abroad for 4 months. During this time, I used prepaid SIM cards for mobile service on my iPhone 13. 

After getting home, I put in the original Koodo SIM card, and it half-works. Normal texting and calling work fine.  Even stranger,  the top of my phone interface still reads ‘Koodo - LTE/3G’ with the bar reliably showing weaker/stronger connections depending on my location. Visually, nothing would imply that I wouldn’t be getting service. Yet whenever I switch off Wifi or try to use data outside, nothing connects. Search engines like Google, social media apps, everything: nothing works. 

I’ve looked through my settings a dozen times and it all seems to be in order. It recognises Koodo as my carrier, I’ve got roaming data turned on, and my APN settings seem to be filled in as suggested (just the APN at sp.koodo.com, user/password fields blank). I even reset my phone’s network settings to no avail. 

I’m lost on how to remedy the issue, since there’s no clear indicator into what’s actually wrong. 

Hope this is posted on the right forum, by the way. Wasn’t sure which one fits best.