Hi there,
I've got a dual wan setup on my RB450G (both ISP's have a dynamic IP addressing to me; although it will generally stay the same unless there network crashes or my equipment is off for a long time.)
The way in which the network is currently setup is the following:
WAN 1 = VoIP only and failover if WAN 2 goes down
WAN 2 = All other traffic and failover if WAN 1 goes down

I have a VoIP PBX (running windows, 3CX PBX software) from the static LAN IP of 192.168.0.200 - all traffic regardless if its VOIP or not, will go over WAN 1 (this is how I want it).

The problem I'm facing at the moment seems to be random (i.e. issues can happen any time without warning).
1) VoIP calls (both in and out) to my provider will not route correctly; they will simply fail regardless if STUN is used or not.
2) If only have one WAN connection running (i.e. other disabled) there is no problem what so ever with the traffic, so the failover's are working correctly.
3) When using both WANs, sometimes the PBX will work for weeks without issues sometimes it will not work at all right from the second of enabling both WANs.
4) During these issues, If I check the external IP being used, it will show WAN 1 (which is correct) but when trying a call; its almost like the call gets 'lost' in the network and returns an error. From what I can see on my wireshark log, is that the call goes out via WAN 1; but there is no trace of it coming back through WAN 1.


If someone could help me that would be great; just let me know what parts of the configuration you need to see.

For my experience, the dual wan game is most of all in
/ip routing export
/ip firewall mangle export

... assuming that if sometimes all goes right, your addressing, nat and filter should be ok