Question
What NAT configuration does cPanel support?
Answer
cPanel only supports 1:1 NAT configurations for IPv4 addresses. This means that there can only be a single public IPv4 address paired with a single private IPv4 address and vice versa.
cPanel also requires a working NAT loopback (hairpin NAT). This means that the server needs to be able to reach its external NAT IPs.
This is noted in our documentation:
https://docs.cpanel.net/knowledge-base/general-systems-administration/1-1-nat/
If you use a NAT environment, your server must reside in a 1:1 NAT configuration to
install cPanel & WHM.
https://docs.cpanel.net/installation-guide/system-requirements/
Networking requirements
...
A 1:1 NAT and NAT loopback configuration if you server resides in a NAT-configured network.