All,

I've tried searching and have found similar posts before, but I have yet to find a real 'solution'.

I'm running Kamailio 6.0.1 & RTPEngine 13.3.1.7 (on a Linux VM)  as a "SBC" (at home) using the config from: 
https://github.com/voiceboys/sbcOS/blob/version_2.0/var/www/html/alpine/config/a0%3A36%3A9f%3Ae7%3A6a%3Ae2/etc/kamailio/kamailio.cfg

Except that I've added the following:

mhomed=1
modparam("rr", "force_send_socket", 1)

The SBC is dual-homed: one interface on the local LAN and another interface directly on the Internet/WAN (real public IP).

Everything works fine, EXCEPT if the remote end (the side on the WAN/Internet) hangs up first. If they do, the BYE never makes it past Kamailio to the local PBX and/or phone.

https://users.openser.narkive.com/1aK7n8Il/sr-multihomed-kamailio-and-enable-double-rr#post8 suggests to use $sht to save the information needed, but I have no clue where in the config to put that.

Any help would be greatly appreciated.