@zvirus well done, good for you. I had a nightmare job working out what I was supposed to be doing trying to get stats from my ZyXEL VMG 1312-B10A modems (in modem-only mode), four of them [!] connected to my Firebrick FB2700 router. The router was unsurprisingly not copying stats info packets through from the admin interfaces of my modems to the the main LAN so I could access them and vice versa. Another problem which I never solved was that the modems’ admin interfaces were not fully configured properly for IPv4 in that the config could set up an IPv4 address for the admin i/f and could define a netmask but could not as far as I could see define a default gateway. The breakthrough in my case was the idea of getting the router to rewrite the IPv4 headers of packets intended for the modem so that the source address was something that referred to something chosen to refer to the router itself (not the original source address, ie. the sending machine in the main LAN, as that was too hard for the ill-configured modem to cope with); this was a source address that was such that when a packet was replied to, the return packet would have a destination address within that link’s address range according to the netmask and would not require lookup of an in this case non-existent default gateway to route the packet off the link. A modem’s admin i/f is at 192.168.n.1 where n is 1,2,3,4 according to which modem it is, and the router’s modem-facing i/f address on that link is 192.168.n.254. The router forcibly rewrote the IPv4 headers by using rewriting firewall rules combined with NAT so as to be able to remember the redirection required for the returning packet.
