P2P and sub-optimal NAT mapping

Troubleshooting
1

“connectd -n” reports:

Your Router has sub-optimal NAT mapping, you may have reduced performance.

but I can’t find any explanation of this phrase in the documentation. Does the software prefer a NAT router to maintain the source port number across the NAT? If so, why does source port randomization imply reduced performance?

A subsidiary question: is it the case that a P2P connection requires that at least one end of the link has a public non-NAT IP address?

2

Sub-optimal NAT mappings may make it so you can only connect to those endpoints via Proxy. The next desktop release will have automatic proxy fail-over, so in those cases you may see reduced performance as compared to a direct P2P connection.

P2P connections do not require public IP addresses. But they do require the ability to map the ports on at least one endpoint.