Sun Feb 12, 2023 8:14 pm
You successfully neutralized your firewall (by disabling #6 and #14 you now allow pretty much everything; probably not the best plan), but other than that, it's hard to tell. The image doesn't seem very clear. Is the server behind second (blue) router or not? Its LAN is connected to it, but its WAN goes to the mysterious yellow thing that's between first and second router, so maybe the server is not really completely behind the second router?
In case it is behind second router, you have two options:
a) Forward ports from first router directly to 192.168.66.x (whatever the server has). First router must know where 192.168.66.0/24 is and second router must let it pass.
b) Forward ports to second router (192.168.88.52) and add another forwarding to 192.168.66.x on second router. This will work even when there's double NAT and first router knows nothing about 192.168.66.0/24.