Evening all,
A bit late to the party on this (by about 16 months by the look of things) but recently ran into this exact problem - namely a PPPoE router (Asus RT N16 running Tomato firmware) and a Draytek Vigor 120 modem not playing nicely with my VSS 3. I seem to have had more luck than most in that I could get a working SS connection, but it was somewhat unstable, dropping twice in two days (and the second time going to a flashing red power light and a solitary amber internet light. Not happy, required a full reset and re-synch). Enough, I thought, there must be a way around this. My solution was the following:
1) Ditch the Draytek.
2) Find an old PPPoA modem router box (if you don't have one you can get a TP-Link one online for about £15). Note it will need to be one that has more than one LAN port and ideally supports a DMZ.
3) Set that router to connect to the internet using its modem in PPPoA mode (as if you were setting it up from scratch frankly) but ensure it is on the 172.16.0.0 network on the LAN side (i.e. give it an ip address of 172.16.0.1). Make sure the connection MTU is 1500.
4) Give the VSS a static IP of 172.16.0.2 and make it the DMZ host. (You do this on the modem router. Note also this is simply me being lazy and effectivley opening all ports on the router to the VSS with the exception of any mentioned in point 9 below. Saves me having to go through the list of required ports as they are all already open and pointing at the VSS.)
5) Plug your VSS into one of the LAN port on the modem router.
6) If your existing router (the one you were originally using with the Draytek 120) was already using the 172.16.0.0 network then change it to the 192.168.1.0 network. If you need to do this then make sure you also update the DHCP server to now serve IP addresses on the 192.168.1.0 network.
7) Plug your existing router's WAN port into one of the modem router's LAN ports. Make a note of its mac address on the WAN side beforehand if you can. Change this router's WAN interface to accept a DHCP address.
😎 On the modem router give your existing router a static IP address of 172.16.0.3. (This is why you needed to MAC address)
9) Make a note of any ports you were forwarding on your original router, and forward them on the new modem router box - BUT MAKE THEIR TARGET 172.16.0.3 - i.e. your original router's WAN interface.
10) Plug all of your existing kit back into your original router
11) That's it!
So what you end up with is a PPPoA device connecting to your ISP with an MTU of 1500 which you are plugging your VSS and your existing router into. This solves the VSS connection issue, and allows you to keep your existing PPPoE router you love so much.
In terms of the network, all the of traffic on your inner 192 network (i.e. second router) can happily connect to the outside as it simply pushes any traffic not on the 192 subnet up the WAN port, and because your two routers are on different (and not intersecting networks) you won't have any collisions.
Finally, any forwarded ports, because they are now "double" forwarded, will work as before - just with an extra hop. It all works flawlessly for me and I now have a working VSS, get to keep my beloved old router, can configure everything like I used to before from the WAN side - and have the added benefit of a proper DMZ that I could plug a wifi access point into (i.e. plug it directly into the modem router) to act as a guest wifi host if I chose to. All for an extra spend of £15. Or £0 in my case as I already had an old PPPoA modem router hanging about.
Oh, and really, everything does work. Firstly, it works because it should (no router collisions due to the separate networks), and secondly I tested it over a number of weeks; I have successfully made and received skype video calls, facetime calls, connected to my VPN at work etc.. from within my inner 192 network. No issues. And my SS has not dropped once.
I appreciate that it's not a solution for all as it does involve using a second modem-router box. But it got my network working, and hopefully it may be useful to other people.
Dave
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