No signal with prepaid SIM card in Israel

Hello community,
I have an issue that I can’t solve on my FP4: Currently traveling in Israel, I bought a prepaid SIM card to use but am not able to access a mobile connection. The phone is working and I installed the latest update, which had no impact on my phone with the German SIM I am normally using. I also tried adjusting the APNs manually as well as selecting the network manually. Nothing helps. The ! in the signal sign won’t disappear and I can’t connect. Has anyone experienced something similar and might be able to help with their input?
Many thanks and best wishes,