Port fordwarding and other issues

Hi sorry to bother you, I have a problem with port forwarding.
I'm sorry for my english.

my network structure is as follows: router of the ISP provider with public address on the wan and internal network, to which the linksys EA-3500 with openwrt and with lan is attached on the wan port, to which a NAS ( is attached which acts as an openVPN server and does fetchmail pop for an external email account and which uploads the mail to the NAS mail server. openwrt is freshly installed and with default configuration, out of the box.

I created (using luci) a port forwarding rule in the "firewall" section that redirects incoming udp traffic from the openwrt wan and forwards it to the nas ip, but the forwarding does not occur and the vpn connection fails. I certainly activated the forwarding of the openvpn udp port from the provider's router towards the openwrt wan IP.

Furthermore, fetchmail from the NAS doesn't work, I assume that outgoing traffic is blocked because if I connect the internal network directly to the provider's router (excluding openwrt) everything works. I didn't set anything on the output on openwrt, leaving the default configuration.

I'm not very expert in openwrt, but by testing with pfsense the VPN port forwarding works and fetchmail downloads the mail.

there are definitely some settings to do on openwrt but after hours of reading documentation and forums I couldn't figure it out.

kindly can you help me

Thank you

What is the purpose of the OpenWrt router in your network? Are you able to remove the ISP router and use the OpenWrt router exclusively?

Please connect to your OpenWrt device using ssh and copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have:

ubus call system board
cat /etc/config/network
cat /etc/config/wireless
cat /etc/config/dhcp
cat /etc/config/firewall
1 Like

Hello and thank you for your kind reply.
I think I've figured it out and the solution is simply that the NAS had the wrong gateway IP. my mistake.

Thanks again for your help and I apologize for the inconvenience.