Data Roaming Problem

I'm using iphone 12 pro (A2407) with 2 lines (physical sim for business, and e-sim for private). (IOS 14.4)

I didn't notice any problem in my home country Turkey for any usage, but during a trip in Nigeria last week, I started to face problems for roaming.

I couldn't succeeded for DATA ROAMING at all.

After getting out from the airplane, none of the lines joined to the local networks automatically.

I turn-off and on the the phone but didn't work.

Both lines joined after I changed network selection to "Manuel" .

But both lines were joining only 3G for data, and was UNFUNCTIONAL for data usage AT ALL.

I was able to receive and make calls but was unable to use data connection.

I tried all possible solutions:

+Hard - Soft reset.

+Take out and re insert Sim.

+Changed from LTE to 3G.

+Reset Network Settings.

+Called carrier and made update of settings for both lines.

To test the situation, I tried my sim card with my friends I phone 7 It worked. (IOS 14.3)

I tried his card with my phone, didn't work again. Connection was 3G (as his card only supports 3G).

I couldn't check e-sim as there were no other phone with e-sim capability.

Being out of data usage doesn't only mean to be out of social media or business, but from maps, directions uber & payments etc.

It was a very bad experience and was dangerous in some cases.

Any solution for this ?