Problems with phone calls and text messages

Hello,
I installed Murena 3.5-a1520260211580868-official-FP6 on my Fairphone 6. But the problem was also present in Murena 3.4.
I am largely satisfied.
However, the phone function is prone to connection problems.
After a while, the phone and text messaging disconnect without me doing anything.
When someone calls me, it goes to voicemail and I can’t make any calls.
I have to restart the FairPhone 6 for the phone and text messaging to work again.
This is a nuisance for a phone that is supposed to be used for making calls.
Have you encountered this problem?
I am with the operator Sunrise in Switzerland.
Thank you for your help.

Perhaps have a look at our discussion here:

Unfortunately, the proposed solutions in that thread aren’t working for me, When this issue occurs, I usually have to go in airplane mode for at least 30 seconds then it’s working again (80% of the time), but for a few hours and then calls or/and text messages are not working anymore. the strange thing is that I can sometimes send SMS to someone and they will receive them, but if that persons send me a SMS I won’t.

Maybe this is a firmware issue ? But this should be a priority for /e/ OS team, as a phone should be able to make phone calls and text messages (before being able to use anything else)