Why can I only get 3G when roaming Canada, Australia, Portugal? And even with 3G WhatsApp can’t work

[Dai13]

Attracted by the chance to use my data allowance in a range of countries I opted for O2, but so far in Canada, Australia, Thailand, Mexico and Portugal, all countries where it should work, I am getting only 3G service and that’s not able to support WhatsApp, let alone more data hungry apps.

So far it’s only been useful in USA and Netherlands for me where I got 4g/5g.

Are the O2 roaming agreements only for the 3G networks in some of these countries?

I’m surprised 3G can’t support WhatsApp messaging too, any ideas if I might have a setting wrong or something. Works fine over 4g/5g/wifi both home and in USA.

Any help or advice very much appreciated.

[MI5]

@Dai13 

Many times, travel restrictions are due to the roaming networks, so it's always a good idea to do a manual network search and try the different networks offered by the phone. Some work much better than others.