[SR-Users] double_rr issues

[Roman Dissauer]

I’m experiencing issues with kamailio 5.1 in multihomed config:

two machines, latest debian stretch, latest kamailio 5.1, exactly same config (verified with diff)
both machines have an internal and an external network interface. Only thing different is that they are in different datacenters.

on one machine everything works perfect, on outgoning calls rr parameters are added perfectly right:
Record-Route: <sip:yy.yy.yy.yy;transport=tcp;r2=on;lr;nat=yes>
Record-Route: <sip:xx.xx.xx.xx;transport=tcp;r2=on;lr;nat=yes>

where yy.yy.yy.yy is the external ip and xx.xx.xx.xx is the internal IP

on the other machine I only get:
Record-Route: <sip:xx.xx.xx.xx;transport=tcp;lr;nat=yes>

even if I set enable_double_rr to 2 I get:
Record-Route: <sip:xx.xx.xx.xx;transport=tcp;r2=on;lr;nat=yes>
Record-Route: <sip:xx.xx.xx.xx;transport=tcp;r2=on;lr;nat=yes>

I already checked with traceroute that the routing to the destination IP Adresses are going through the external interface.

maybe someone has a hint for me.

Thank you all in advance!
Roman