No sim card installed

Hello, I encountered this problem, I’ve been using the iPhone 7 for about six years, iOS 15.8.1, the fact is that I was shown a notification that the SIM card was not installed in the previous version of iOS, rebooting the device helps for a couple of minutes, I did resetting the network settings also helped for a couple of minutes, then I updated to 15.8.1 and everything worked fine for about two weeks and today I have the same problem again, does anyone know how I can solve it?