I restored from ISO (on the same hardware) to get rid of the old partition scheme. Comparing directories from before/after that, I noticed a problem in "/var/ipfire/dhcp/dhcpd.conf": option routers 192.168.120.1192.168.120.4; There are two IP addresses in one line. In the old installation, this looked like this: option routers 192.168.120.4; "192.168.120.1" got added. This is and has been the green IP. I have no idea where the 192.168.120.4 was coming from. DHCPD has never been used. So, it seems like the restore process mangled these two entries.
PS: 64-bit Core 161 before/after
Did you restore a backup and still configure the DHCP server in the setup?
I had the installation process do the restore from the ISO. Configured the green interface to use DHCP as a client, but did not configure a DHCP server.
*** This bug has been marked as a duplicate of bug 12757 ***