I am using 3CX version 11 SP4. I have about 20 Cisco 504g phone all running the 7.5.2 firmware all on the same local subnet at the 3CX server. One particular 504g started getting its IP address blacklisted dozens of times in just a 12 hours period. I tried re-provisioning the phone, resetting to factory defaults, none of which seemed to help. I then decided to whitelist the IP address of that phone, which seemed to stop the blacklisting, but now the computer that is connected into the PC LAN port on that phone keeps losing its network connection every 20-30 minutes until the phone is rebooted. I would like to be able to find out what is causing the blacklisting so I can solve the original problem and not whitelist the IP. Any ideas?