Are you with Play or any company that uses their network?
Unfortunately, this issue with the necessity of disabling 4G connections in order to be able to recognise the caller has been reported on Play.
But I have not seen any reports on rebooting.
Thanks for lightning-fast replies! Yeah, that page doesn’t lead to anything else… Maybe it sends feedback to Fairphone, but nothing is communicated to me.
Have you noticed the ticket registered under your support account?