the pam ID is tied to public IPs, the IP addresses that ISP's assign to all the devices connected to them. That's why two devices connected to the same wifi router have the same ID, and why switching wifis or using a vpn changes your IP. ISPs that frequently change your public IP can cause your ID to change randomly, try documenting your current IP, then seeing what it is after your ID randomly changes while you're still connected to the same network.