Access From: Type: Zone/VPN/Uplink
Interface: Uplink main
Target: Zone/VPN/Uplink
Interface: Uplink main - IP: publicip here
Filter: Allow
Service: Any/TCP/0:65535 (as the app tries to connect from any port to the local 6164)
Translate to: IP
DNAT: NAT
Insert IP: 10.10.5.219
Port Range: 6164
The way I read this is:
The rule above states ALL connections to ANY port (0-65535) to your Uplink main interface (1.1.1.1) from the outside will be sent to IP address 10.10.5.219 port 6164
Which is almost a DMZ type rule.
You should just direct traffic designated to a few ports (or even just port 6164) to your internal Ip address.
When you say "as the app tries to connect
from any port to the local 6164" you are talking about the Source, not the Destination.
The
Service: Any/TCP/0:65535 should be
Service: Any/TCP/6164 as this entry is for the
Destination port, not the Source port.
Also, your external (eth3) is 1.1.1.1
Is this what you fixed it to or is this the value shown because you are running your Red interface as PPPoE and your modem is in Bridge mode.
I hope it helps to enlighten things a bit.