HTC Desire 820 randomly stops detecting the SIM card

Hi everyone, my old HTC Desire 820 has a problem. It randomly stops detecting the SIM card from yesterday (I checked another sim cards and another device, it's a smarthphone fault, not a sim card). I looked through various tips in google what could be the reason and how to fix them, but they didn’t help. I will add that sometimes for example for 2-3 minutes everything is okay the sim card works well and a moment later when I start using a smartphone I got info “No sim card, no service”. Any help would be appreciated.