Since that's shown as a linked port forward I assume you have a firewall rule in place. Are you seeing anything in the firewall logs?
Steve
I don't know since all filter logs change so fast … anyway it was my fault ... had to connect to an external vpn server first then tried to connect via ssh to my host and it worked. Sorry for the trouble. Strangely though I hadn't to do this when using the Zyxel router ...
Connecting to my WAN IP address with a PC from the LAN directlly (i.e. not by using an external vpn) results in a connection timeout.
Thank you for your support stephenw10 ;)