I had yet another go at this (i.e. accessing the 192.168.1.1 Management Interface on a Zyxel VMG1312-B10D, via a Draytek Vigor 2830n). It nearly works - but I still have a problem to solve.

Here is a diagram of the network at the property in question. The vast majority of the clients use Wifi (i.e. Phones, Tablets, Laptops, I.O.T stuff). There is a single wired client (a YouView box). The main LAN is 192.168.200.0/24 and DHCP is used. A site-to-site VPN connects back to 'base'.



What I have done for this experiment, is add a second connection between the Zyxel and the Draytek. The idea is, that this comprises a 192.168.1.0/24 network (created as port-based VLAN1, with inter-LAN Routing enabled).

Initially, this burst into life - and requests for 192.168.1.1 successfully targeted the Zyxel - but it was short-lived. Eventually, the connection to the internet became unusable, until the 2nd connection was removed, at which point, it sprang back to life. ThinkBroadBand's 'Quality Monitor' showed the effect quite graphically.

I thought I had fixed it - by turning off IGMP/Multicast support on the WAN and adding a vast array of firewall rules (none of which ever seemed to trigger!...)

The remaining problem, is that will not power-up and establish a connection to the Internet in this state.

You have to wait for the connection (to the ISP) to be established and then plug the second connection in
Presumably something about the PPPoE initialisation is upsetting things - maybe some kind of broadcast, that is looping around my two inter-connects and ignoring my firewall rules? From what I've gleaned from Wikipedia , this broadcast may be Ethernet-based, not IP...

Any ideas to work around this :?: