Roaming problem - I have to manually select a network operator otherwise there's no connection

[HoloPuff]

I've had this problem with Public Mobile for years. It's persisted across several Android devices. I currently have a Samsung S24 Ultra. 

The problem is weird, here is what happens. It only happens when roaming in the US. 

I see a 5G symbol for a fraction of a second, then it's gone. Then it's back, and gone. This repeats forever. 
If I go into settings, to network operators, disabled "Select Automatically", then "Scan", then pick an operator from the list, then I have a stable connection. But only as long as I'm on that network. This is a big problem when driving, I have to repeat this process every 10-20 minutes when that specific operator loses coverage. 

In a nutshell, "Select automatically" for the network operator doesn't work. Manually selecting an operator works, but is very annoying. Any idea how to fix this? Because I'm really sick of it, and if this is an carrier problem, I will switch carries to get this resolved. 

[DennyCrane]

It's because AT&T 5G doesn't work, but it still tries to connect. You can either set your phone to 4G preferred and leave network selection on automatic (this is my preference as it lets you bounce between T-Mobile and AT&T) or you can leave it on 5G and manually connect to T-Mobile.

[Dunkman]

@HoloPuff 

Public mobile uses two US carriers:  AT&T and T mobile.  

Your experience seems to be consistent with other PM customers.  The 5G network is spotty especially with AT&T, but better with T mobile (if available). 

Some customers recommend manually selecting 4G/LTE network  (not Auto or 5G) while in the USA and choose either T mobile or AT&T as your carrier depending on the area.

These issues are due to PM's US carrier partners.  You could choose a different Canadian carrier with different US partners.