Port forwarding help for a noob

So I have read many topics to try and get a way forward with the issues I am having with port forwarding on Openwrt. I have followed all the instructions on how to configure it but none seem to quite cover my build. I have an ISP router which does nothing other than link by wire to my Openwrt router, I have even switched off the firewall on the ISP router. On the Open WRT router I have multiple VLAN's configured but only 1 needs port forwarding to. I have a dedicated server used for gaming which needs port forwarding to and also multiple PC's on the same VLAN that need port forwarding to be able access the server.

Now I have followed the standard port forward configuration style which I had setup previously before I configured the VLAN's etc and all the same rules configured on the PC's which worked with the server previously but still cant open the required ports. I have tried telnet ing between the PC's and server to see if the ports are open but to no avail.

I could do with some tips if anyone has configured port forwarding to a VLAN on a router that is not the ISP router. Also any advice on things and ways to check other than the obvious online port checker and telnet.

I am no guru at this by any means and setting up the VLAN's was my crowning achievement but this port forwarding issue really has me stumped. For any proposed responses pls be gentle with me and use leyman terminology.

If your OW device is behind another device I believe you need to get the forwarding on the WAN facing device to work. I assume you don't have to option to make your OW device that WAN facing one (ie remove the ISP's router).

Unfortunately not, my VLAN router does not have a modem so cannot be ISP facing.

Please run the following commands (copy-paste the whole block) and paste the output here, using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have

ubus call system board; \
uci export network; uci export dhcp; uci export firewall; \
head -n -0 /etc/firewall.user; \
iptables-save -c; ip -4 addr ; ip -4 ro li tab all ; ip -4 ru

Private IPv4: (10.x.y.z) (172.16.x.y - 172.31.x.y) (192.168.x.y) and (100.64.x.y-100.127.x.y)
Private IPv6: Link Local fe80::/10 basically every address starting from fe80
ULA fc00::/6 (basically fc.... and fd....)