[tor-relays] Snowflake-proxy restricted NAT

[dmz21]

Hi,

I've been running a Snowflake (the stand-alone Go-proxy kind build from source) as a Debian service.
I was working fine before, showing a handful of anonymous connections per day.

Recently it shows a new log message: "NAT type: restricted" after "starting" and I have not seen any new connections.
I'm guessing that a restricted NAT does not allow any client to connect to my VM. Please tell me if I'm wrong.

I don't think that I have made any relevant changes to my network or hypervisor setup, recently.
I don't know how to configure my OpenWrt router such that I have a suitable NAT to a specific IP in my DMZ.
Can anyone tell me what I could try in order to restore my Snowflake-proxy to being useful to others again?

kind regards and thanks