A small number of users at C-Servers has seen an unusual behaviour on NAT bridging with our VirtFusion platform - NAT IPv4 usage sometimes works outbound correctly, but stops working inbound. 

The symptoms are:
- NAT IPv4 appears as working for regular HTTP/HTTPS connectivity;
- but the SSH Service Port rule on NAT IPv4 does not work,
- or any of the existing customized NAT rules do not work or have stopped working,
- and restarting or reinstalling doesn't help.

Rules are managed automatically at iptables by the VirtFusion platform and the libvirt network bridge, without any interference on those, at any moment, from C-Servers. What seems to happen on these cases is that VirtFusion "forgets" the existing rules, for some reason, and partially drops NAT connectivity in a silent way for the end-user (as of February 18th, 2026).

A user has discovered the solution for the problem: creating a new rule on a new port you know you will not need actually refreshes internally the table for the existing NAT rules, reallowing NAT IPv4 Inbound connectivity to work again. 

To create it, just go to the Network area on the VirtPortal and, on the "Configurable Ports" section (just below "Service Ports"), you just insert any new port to any new destination, e.g. 50498 to the internal port 8400, and click Update. This has been shown to work by C-Servers customers on the VirtFusion system.

Remember to allow a period of up to 15 minutes for NAT rules to be updated.