RUTX50 > VeloCloud Edge & Zscaler GRE

Good afternoon,

I’m trying to establish Zscaler GRE tunnel from a VeloCloud SDWAN Edge that is connected behind a RUTX50. The RUTX50 is connected via SIM 1 to WAN.

I did tcpdump -i br-lan proto gre and see that GRE traffic is sent out but there’s no return traffic.

I tried
iptables -I INPUT -j ACCEPT
iptables -I FORWARD -j ACCEPT
as well, but still with the same result. GRE tunnel from VeloCloud is not established.

I reduced the MTU for mob1s1a1 to 1300 with the same result.

Zscaler GRE is working fine from the same VeloCloud Edge via different DSL circuit.

What is there that I haven’t looked at?