so far i got no prob with UM. me too just switched from M 2months ago together with all my sub lines. found out their coverage now quite good indoor and outdoor.
call quality good as well. but mostly on whatsapp calls or imessage call. loud and clear.

mostly at seri kembangan, sunway, klia, east malaysia ie kuching, bintulu, sibu and KK

compared to few years back,  i was shocked that UM improved a lot.

sometimes when 4G not sufficient, i will try to switch on 5G. so far i got no prob connecting myself with others.

I think lately u mobile service has been deteriorating. No 5g service, despite full 5g on my other celcom line.

Internet also a bit unstable. Has been a few weeks at least.

It was perfectly fine before

ya i cannot set 3g using iphone. This is false advertisement. They claim can do 4g data roaming but this is shit