AX12 RAX120 port forwarding

[fcacarminati]

Hello,

   total newbie, so forgive me if this is a stupid question. I have a modem/router (internet box Orange in France) and I connect my RAX120 with an ethernet cable from the modem. I have dyndns and would like to forward a port through the modem to a device attached to the RAX120. I have setup port forwarding both on the modem and the RAX120 in router mode, but it does not work. If I connect the device to the modem, it works. But I cannot go from the modem through the RAX120 router. 

I hope this is clear enough. Any hint would be appreciated. 

Thanks and best regards,

Federico Carminati

[FURRYe38]

Your ISP Modem already has a built in router and wifi. This would be a double NAT (two router) condition which isn't recommended. This would be a double NAT condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge or modem only mode. Then use the NG router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ/ExposedHost or IP Pass-Through for the IP address the NG router gets from the modem. https://kb.netgear.com/25891/DMZ-on-NETGEAR-routers
https://kb.netgear.com/24086/How-do-I-set-up-a-default-DMZ-server-on-my-Nighthawk-router
3. Or disable all wifi radios on the modem and connect the NG router to the modem, LAN to LAN configure AP mode on the NG router.
https://kb.netgear.com/20927/How-do-I-change-my-NETGEAR-router-to-AP-mode
https://community.netgear.com/t5/Orbi-WIFI-6-AX-AND-Wi-Fi-6E-AXE/Procedure-for-Factory-reset-of-RBS8...
Try option #2 first...
https://kb.netgear.com/000061927/What-is-the-difference-between-router-mode-and-AP-mode
https://kb.netgear.com/26765/Disabled-Features-on-the-Router-when-set-to-AP-Mode