I have same problem in my phone M30

[Samsung_mvR4s0N]

I am facing 4G network issue after Android Pie Update in Samsung M30.

[Parm0708]

I am not facing any problems in my M30 after pie update

[profficial001]

it may be network provider issue..or just reset ur network settings once and check!!

[Nishitkohli]

I hope Samsung will resolve your problem soon .

[Sanjayvarsat]

I am facing network issue in M30 with Vodafone.. same sim is good network strength in other device..contacted network provided but as per them they don't have any issue in network..