Physical SIM card problem

Hi,

I have a SIM problem, I hope that you could help me out. When changing from S23 to Fold8, I opted for e-sim, instead of sim card. After 2 weeks with e-sim, I find that the network connection isn't stable at all as it disconnects often. So I insert the physical sim card to the Fold8, and I activate that sim, and deactivate e-sim. The SIM card worked well on the old S23 phone. Now, with Fold8, I can no longer connect to Internet, nor make a phoned call. It says : "Not registered on network".

Do you know what I should do to re-use my SIM card again ?

Thank you for your help.

Do you have any issue using e-sim on the Fold8 ? Is it possible that my phone is defective ? Everything else works well.