For the very first time i tried to selfhost a static site (lighttpd + duckdns) but I’ve failed… Is it even possible to selfhost a static site from “router 2” while i’m behind two routers? “Router 1” is from ISP and i have no possibility to change any settings except subnet, standard gateway, dhcp on/off and DMZ. -> no port forwarding. "Router 2 is Asus with port-forwarding available and i’m using an OpenVPN configuration on it (if that matters). DuckDNS could see the external ip from R2, but i couldn’t access it.
Probably because the ISP modem/router has limited capability.
I’ve done 2 routers like this for years (out of laziness more than anything) because cable modem router suck from a capability standpoint.
The actual cable modem can run in passthrough mode though. Look up the model and find the docs. Should be a quick and easy change, or your ISP at least should able to change it. It would be absurd if not.
the ISP locked their router. I have to go the the ISP’s site, login and change settings there… can’t even change DNS on ISP-router.
That’s a bummer. Have you asked them about running it in passthrough mode?
No I haven’t. First i got to educate myself what these different modes are…
Passthrough in this sense just means that the ISP cable modem only acts as a modem, handing off all traffic to your router to control. Essentially it just disabled NAT so you won’t have double-NAT’ing happening. It’s a standard setting on all cable modems, so I know that part is possible, but it’s more about getting your ISP to enable that if they have it locked.
that’s exactly why.
Is the ISP device a cable modem or is it fiber?
You may be able to replace it with your own stuff
it’s fiber.
Do you have a username and password for PPP? You could replace the device with something with a SPF port
Another option is that you could turn off masquerading (NAT) on the Asus router. This may not work but if you have different IP ranges on each device theoretically it would avoid double NAT