I updated my Elastix server's IP address. I then updated my ATA's proxy server to the new Elastix server's IP address. The ATA can't register to the extenstion and go online, it only says offline or can't connect to the login server? I did change my router's port fowards aswell? I updated Elastix's IP address from 192.168.1.160 to 192.168.1.164. 192.168.1.160 was the IP address I set for Elastix Version 2.3.0 Release 5 which is running on my VM in Proxmox. I simply logged into 192.168.1.160 with the browser GUI, went to Elastix/System/Network/Device/Ethernet 0/IP Address: 192.168.1.160 and changed to 192.168.1.164/Apply Changes/OK. I then went to my ATA Linksys PAP2T/Line 1/Proxy and Registration/Proxy: 192.168.1.160 and changed to 192.168.1.164/Save Settings. This will send the ATA packets to the VoIP server's extension 3000 which has the same password in the ATA's extension settings and Elastix's PBX/Extensions' secret. I don't use a firewall. In fact, I have set the router to DMZ to allow all traffic in an attempt to fix the issue. I can ping and access via browser GUI the ATA, Proxmox, Elastix and the router. Yes, all the correct ifconfig details come up. I actually reboot the Proxmox server every night when it's turn off automatically with a cron job at 2200 and then the BIOS turns it on automatically at 0800 (watch out for the BIOS System Time which is changed by the OS' Proxmox clock to UTC(GMT)). Everything pings but still no ATA connecting to the server extension? I only changed IPs, so maybe Proxmox has a firewall?...I will need to research. I didn't change any passwords which is also a common resolution, but I checked this numerous times even though I shouldn't really need to.