My VOIP phone won't use the L2TP tunnel

RouterOS Beginner Basics
1

Hi,
I’m definitely a newbie - trying to use my RouterBoard RB750r2 after consumer routers (Netgear) is pretty hair raising :slight_smile:

I’m currently behind a 4G NAT router so to make my Snom VOIP work properly I decided to set up a L2TP tunnel to my VOIP ISP who is Andrews & Arnold, using my RouterBoard.
I got a little help and set up the L2TP tunnel and it appears to be established with a (local) IP address I can ping.

In Firewall, I set up a Masquerade, Chain srcnat to the L2TP tunnel, but to no avail, the phone insists on registering and sending data via the normal ether 1 route, not via the L2TP tunnel.
How can I make the phone, (on 192.168.88.253) use the tunnel?
Do I need to change any settings (e.g. Gateway?) on the phone to make this work?
I’m using Winbox to administer the box.

Grateful for any hand holding!

2

This can be done relatively easily, your problem is that to get to the internet your router is routing through your 4G provider.

You need to add a route the same distance as your default route however give it a routing mark to look for (voip for example).

Next you need to actually mark your packets you want going down the L2TP tunnel using Mangle
add action=mark-connection chain=prerouting in-interface=XXX new-connection-mark=voip passthrough=yes src-address=VOIP.PHONE.IP.HERE
add action=mark-routing chain=prerouting in-interface=XXX new-routing-mark=w3z passthrough=yes src-address=VOIP.PHONE.IP.HERE

Finally, adjust your src-nat rule so it looks for the routing mark as well just for completeness.

3

Thanks Steve, I assume I should use a New Terminal to do this (I’m using the Winbox interface)?