Asus RT-AC66u NAT loopback is not working

[RubenPortier]

Hello

I'm currently running the latest stable Merlin build 3.0.0.4.374.43_0. I have a server which has a static local IPv4-address 192.168.1.100.

I want to access that server from within my LAN with my public IP-adres. This should be possible with NAT loopback which is supported by Merlin build. I couldn't find any option to turn that on and even on the internet there is less to find about it. I found one forum post on SmallNetBuilder where someone said it is turned on automatically.

But why can't I connect using my public IP-adres. Only using the local IP-adres works to connect to the server.

Thanks!

 

[ParanoiA]

Sounds like a port needs to be forwarded to that static assigned address

 

[RubenPortier]

I have opened the port for example 80 for the web host. Other outside my LAN can access the webserver on my public ip as I have correctly forwarded the port for that. But I can't from within my local network.

 

[Grump]

I have a box in DMZ and I can access it from the LAN with the public IP: port. Also running AC66u.

 

[RubenPortier]

I have a box in DMZ and I can access it from the LAN with the public IP: port. Also running AC66u.

My server is not in DMZ (I can test if that works) because I don't want all the ports open to that server. Only the ones I open in port forwarding.

Does this NAT loopback not work with port forwarding?

EDIT: It doesn't work with DMZ enabled either. Is there something else I'm doing wrong? Looks like the NAT loopback isn't enabled at all.

 

[Bobcat00]

Loopback / port forwarding works with 374.35_4-sdk5. I don't know about the new build. Maybe this is another reason for me to stay with 374.35_4-sdk5.

 

[RubenPortier]

Loopback / port forwarding works with 374.35_4-sdk5. I don't know about the new build. Maybe this is another reason for me to stay with 374.35_4-sdk5.

Thanks for the reply! I did use an older version and it also didn't work. Then I upgraded to the latest stable build but it still doesn't work.

EDIT: After resetting the settings to their default (never did that before) the NAT-loopback is working as it should!

Thanks for the help!

 

[RMerlin]

Is Dual WAN enabled? This might potentially cause issues with port forwarding.

Also make sure that both NAT and the Firewall are enabled on the router. These two are necessary for the NAT loopback.

Also make sure it's not a DDNS issue (that is a common mistake) - test the loopback using your WAN IP rather than the DDNS to isolate the issue.

Another common issue is the firewall on the server which allows connections only from specific IPs.

Finally, connect through SSH, and see if there is any packet hitting the port forward rule:

iptables -t nat -L VSERVER -v

The packet count should increase with each connection attempt. If it does, then it means the issue is either with the server IP or the port you are forwarding, or the server itself.

 

[RubenPortier]

Is Dual WAN enabled? This might potentially cause issues with port forwarding.

Also make sure that both NAT and the Firewall are enabled on the router. These two are necessary for the NAT loopback.

Also make sure it's not a DDNS issue (that is a common mistake) - test the loopback using your WAN IP rather than the DDNS to isolate the issue.

Another common issue is the firewall on the server which allows connections only from specific IPs.

Finally, connect through SSH, and see if there is any packet hitting the port forward rule:

iptables -t nat -L VSERVER -v

The packet count should increase with each connection attempt. If it does, then it means the issue is either with the server IP or the port you are forwarding, or the server itself.

Many thanks for this, but as edited in my last post. Resetting the settings to default fixed my problem.

 

[Bobcat00]

And I see you have an AC router, but I have an N router. So my comments wouldn't apply anyway. Derp!

But glad you got it fixed.