What's new

Router under ISP Modem/router headache

  • SNBForums Code of Conduct

    SNBForums is a community for everyone, no matter what their level of experience.

    Please be tolerant and patient of others, especially newcomers. We are all here to share and learn!

    The rules are simple: Be patient, be nice, be helpful or be gone!

Freddyboy

New Around Here
I changed my ISP (went form cable to Virgin Fiber). I dont have the TV. Just Internet. My new provider comes with it's own modem/router, a moded Sagemcom 5566.

I plugged my old RT-AC3100 Wan into one of the Virgin/Bell Sagemcom 5566 lan port, and disabled WI-Fi over the Sagemcom. I kept the computers and servers plugged to Asus.

My Sagemcom gave 192.168.2.11 to my Asus router. Asus have leased 192.168.1.x to others clients. Everything seems to work fine, except... no port forwarding over Internet. :( And I read by googling that I am having something called a double nat. Which is supposedly bad.

I also found putting Sagemcom 5566 in bridge mode could solve my problems. But nothing like that in the made by Virgin router menus.

What would you do? I want my port forwarding back.. ;)

Any way to use the Virgin only as a modem? PPOE connect with Asus.. it's fiber so I don't know. Is PPOE for DSL only? Argg...

Asus in bridge or AP mode? How? I got Merlin firwmware. Which cable goes into which port of the Sagemcom 5566 and Asus?

Thanks in advance for your help guys!
 
I changed my ISP (went form cable to Virgin Fiber). I dont have the TV. Just Internet. My new provider comes with it's own modem/router, a moded Sagemcom 5566.

I plugged my old RT-AC3100 Wan into one of the Virgin/Bell Sagemcom 5566 lan port, and disabled WI-Fi over the Sagemcom. I kept the computers and servers plugged to Asus.

My Sagemcom gave 192.168.2.11 to my Asus router. Asus have leased 192.168.1.x to others clients. Everything seems to work fine, except... no port forwarding over Internet. :( And I read by googling that I am having something called a double nat. Which is supposedly bad.

I also found putting Sagemcom 5566 in bridge mode could solve my problems. But nothing like that in the made by Virgin router menus.

What would you do? I want my port forwarding back.. ;)

Any way to use the Virgin only as a modem? PPOE connect with Asus.. it's fiber so I don't know. Is PPOE for DSL only? Argg...

Asus in bridge or AP mode? How? I got Merlin firwmware. Which cable goes into which port of the Sagemcom 5566 and Asus?

Thanks in advance for your help guys!

If you can't get into a bridge mode on your Sagemcon you will have to setup double port forwards. First on the Sagemcon give your ASUS a static IP.

Then forward all the external ports you need to forward to the NEW static IP of the ASUS.

On your your ASUS change the LAN subnet to something different if it happens to be the same as your Sagemcon's LAN subnet. From your post it looks like this is OK, but check.

Now go into the port forwards on the ASUS and verify that the ASUS router has the forwards you need to the devices you need.

A less desirable approach from a security standpoint is on the Sagemcon put your ASUS router in its DMZ. Try to make the double port forward work first.

Another less secure approach than double port forwards is to enable UPnP on both devices.

The biggest problem with being double NATed is the issue you are having with port forwarding. Being double NATed will not increase your latency by any amount you can measure or will it impact your speed.
 
I tried another approach.

- I removed Internet login info into the Sagecomm/Virgin
- I created a PPPOE connection under Wan settings into Asus, using the Virgin connection info
- In Asus, I changed MTU and MRU from 1492 to 1500 for the PPPOE this connection
- I kept the cable plugged into Asus Wan and Sagecom Lan port
- I also kept my router IP in the Sagecom advanced DMZ, ut disabled UPNP, DLNA into the Sagecom

Seems to works well so far!! Ports forwarding and everything. What do you think?

And here are a couples sidenotes/questions..

1. Is this the correct way to connect to my fiber ISP?
2. Should I disable DHCP or something else in Sagecom?
3. Is DMZ mandatory for this to works?
 
So to confirm what you are saying, the sagemcom isn’t in bridge mode, it’s routing and you’ve put the Asus in the DMZ? Technically it sounds like you’re half way there, it’s in double NAT, full bridge mode would be ideal and I’d recommend doing that, but if it is working and you are happy then it sounds like it may be secure enough to leave like it is so long as the firewall stays enabled on the ASUS while it remains exposed via DMZ. Just for the record, some fibre providers don’t require you to provide PPoE information to get the connection so that may not be a factor to consider during setup. Anybody else have a suggestion?

1. It’s not perfect but if it works...
2. Disable DHCP on the sagemcom and give the ASUS a static IP within the Sagemcom Subnet? it’s optional, I wouldn’t worry about it because I’d you forget and later decide to directly connect to the sagemcom again you may get confused when dhcp doesn’t kick in and assign your machine an ip. That would waste time.
3. Probably, if this is how you want to do it. By putting the Asus in the DMZ it is not behind the sagemcoms firewall, therefore you won’t need to setup port forwarding on the sagemcom. It’s still not perfect... if you remove the Asus from the sagemcom DMZ then you will need to setup port forwarding on the sagemcom. That said, port forwarding exposes a device to the internet and isn’t nevessary unless you are trying to host a website or game server or something similar. Avoid port forwarding unless absolutely necessary.
 
Last edited:
As I said in Post #3 putting your double NATed router in the first router's DMZ is not desirable and probably not even necessary. Port forwarding isn't as bad as DMZ since it punches fewer holes in your first router's firewall.

I run a double NAT setup and on occassion a triple or quad NAT setup when I am testing things and I never had had to utilize putting any router in the DMZ of another router nor setup portwards and UPnP is off on all routers. I don't have a web server running on my network nor do I game so your needs may vary.

The point being don't puch holes in your firewall if you don't have to. If you find some things are not working then temporarily enable UPnP on both routers and then look in your router's logs to see what port forwards were created using UPnP and then you can try and duplicate them manually and turn off UPnP for additional security.

As long as you are going to run double NATed you might as well make full use of both router's firewalls.
 
Sage come can be briged look for a guide on your model you need to acess the asmin menu for such settings
 
In my opinion, you should find a standalone MODEM that supports your ISP.

I've always had issue with AT&T and Xfinity's all in one combo gateways.

I always buy a separate modem and router.

I wish access points were cheaper, otherwise I'd buy a switch, access point and modem separately too hahahaha
 
Last edited:
FYI: MODEM should actually always be fully capitalized and it stands for Modulation Demodulation. Marketing of course rebranded the term into a word.
Not correct, it is composed from modulatordemodulator
Same as there dont exist pentometers (in one of your other postings), you probably mean potentiometer to reduce voltage on your fan.
 
Last edited:
Where is the dislike button or angry face emoji?

You actually aren't contributing to the conversation by nitpicking autocorrect or the lazy spelling of other users.

I was just letting people know what MODEM stands for.

Please, do not point out my laziness when it comes to grammar or spelling, if my message is still factual, and the human brain corrects when understanding what I am talking about.
People who know the meaning of modem dont need your instruction and the others learned just nothing as they wont know either what a modulator, demodulator, muxer and all those 50-100 years old equipment is.
 
(FYI: MODEM should actually always be fully capitalized and it stands for Modulator Demodulator. Marketing of course rebranded the term into a word.)

Congrats on your course work!

If you Google modem, you'll find it all over not capitalized, including all over Cisco's website and products.

Forums are full of poor spelling and grammar. You're on a fool's errand to correct it. It is best to just lead by example.

OE
 
Last edited:
I changed my ISP (went form cable to Virgin Fiber). I dont have the TV. Just Internet. My new provider comes with it's own modem/router, a moded Sagemcom 5566.

I plugged my old RT-AC3100 Wan into one of the Virgin/Bell Sagemcom 5566 lan port, and disabled WI-Fi over the Sagemcom. I kept the computers and servers plugged to Asus.

My Sagemcom gave 192.168.2.11 to my Asus router. Asus have leased 192.168.1.x to others clients. Everything seems to work fine, except... no port forwarding over Internet. :( And I read by googling that I am having something called a double nat. Which is supposedly bad.

I also found putting Sagemcom 5566 in bridge mode could solve my problems. But nothing like that in the made by Virgin router menus.

What would you do? I want my port forwarding back.. ;)

Any way to use the Virgin only as a modem? PPOE connect with Asus.. it's fiber so I don't know. Is PPOE for DSL only? Argg...

Asus in bridge or AP mode? How? I got Merlin firwmware. Which cable goes into which port of the Sagemcom 5566 and Asus?

Thanks in advance for your help guys!
Ppoe is for Fiber and DSL, not sure about cable
 
I tried another approach.

- I removed Internet login info into the Sagecomm/Virgin
- I created a PPPOE connection under Wan settings into Asus, using the Virgin connection info
- In Asus, I changed MTU and MRU from 1492 to 1500 for the PPPOE this connection
change it back to 1492, otherwise your modem hs readjust all the packets coming from your router.
- I kept the cable plugged into Asus Wan and Sagecom Lan port
- I also kept my router IP in the Sagecom advanced DMZ, ut disabled UPNP, DLNA into the Sagecom

Seems to works well so far!! Ports forwarding and everything. What do you think?

And here are a couples sidenotes/questions..

1. Is this the correct way to connect to my fiber ISP?
2. Should I disable DHCP or something else in Sagecom?
3. Is DMZ mandatory for this to works?

You don't need to remove login information, you can have up to two or multiple instance of PPPOE connection, also change it back to 1492, otherwise your modem has re-adjust all the packets coming from your router to match MTU and MRU to be 1492, before sending. 1500 is only for DHCP based internet or isp which support baby jumbo frames.

You can also check what is your current MTU and MRU on web before changing, make sure router ip is accessible from WAN if you decide to test it.
 

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!
Top