main_icn_My_Vodafone main_icn_Search main_icn_Chevron_right main_icn_Chevron_down main_icn_Close main_icn_Menu social-facebook social-google-plus social-linkedin social-twitter social-youtube main_icn_Community_or_Foundation main_icn_Location main_icn_Network_signal

Other broadband queries

router behind another router

unclebob1
2: Seeker

I've picked up a THG3000 router, which I want to use BEHIND my existing router.

Router A for example has 192.168.1.1 as its internal ip, with a dhcp range 2-10 

It is connected to the internet directly.

 

 

I want to connect Router B such that it picks up a WAN ip from the dhcp pool from Router A, and then has its own internal LAN IP of say 192.168.2.1 with its own DHCP range of 192.168.2.2-10

 

Is this possible with the THG3000 running as router B? I tried to connect a cable between LAN port on Router A to WAN port on router B, but the THG3000 interface couldn't figure out that it had a connection to the internet - but the port was showing as active - so it knew there was a connection.

 

The aim for this setup in case anyone will ask why is that I want to separate the kids devices directly to router A and then have a second network for my devices. Happy for my devices to connect to devices on kids network, but dont want kids devices connecting to my devices.

 

I understand the double Nat problem etc, but this doesn't concern me as I don't do any port forwarding in my use.

View more options
29 REPLIES 29
Cynric
12: Established

I had the following setup with VF:

 

BT Green Cabinet -> THG3000 (192.168.1.1) -> Netgear Router (192.168.0.1) -> LAN

 

This was the easiest and kept the VF (un)helpdesk happy because as far as they knew/cared the THG3000 was connected to them. The nice thing for me was that I could do my own WiFi settings as I required, run my own DNS and DHCP servers and effectively ignore VF entirely. Well entirely except for the awful line speeds.

View more options
unclebob1
2: Seeker

Any ideas on doing it the other way around with the Vodafone thg as the second?

View more options
KeithAlger
16: Advanced member

NAT is Network Address Translation, and it does have the potential to cause you problems since you are using a network router (which is performing NAT) and not a network switch.

 

Your downstream router B will be appearing to the upstream router A as having a single local IP address from it's WAN port.  In many cases, this is good enough that clients on the downstream router can access basic internet services - though there can still be problems caused by data lost from packet headers sent from B to A to the internet, and the addition of VLAN IDs and tags already added when the downstream router sends data through the upstream router (along with password verification and other protocols that will go nowhere).  Using a non-ISP locked router, even in a double NAT environment is going to be less problematic (and non-problematic if you just set it up as an access point)!

 

So a bit more info on why this won't work:

The A subnet will see all traffic originating from the B subnet as originating at router B, and the firewall on router B is quite capable of discarding data packets that appear to be unsolicited (they never get to their destination).

 

Many of the problems that are seen when you have double NAT will just look like (incredibly) annoying quirks, and people just think this is the way that it is, when it absolutely doesn't need to be!

View more options
Cynric
12: Established

.@unclebob1 In fairness to .@KeithAlger did say "potential" but I have been fortunate with double-NAT. I can even connect to my work VPN and do my 9-to-5 stuff without problems. I think the only answer may be to try it and see what happens for you. One thing is that if you don't have the THG3000 connecting to VF then they are not going to help you with any issue as they will not support other modems.

 

 

View more options
unclebob1
2: Seeker

Thanks for the info guys.

 

So I connected the Lan from my existing suppliers router to the wan on the thg3000, but it looks like the thg doesn't know there is a route to the internet there, but does acknowledge that the connection is active! 

I then connect via WiFi to the thg but it doesn't connect out, keeps telling me to login and check connection to internet.

 

I'm not on Vodafone at present (actually looking to sign up tonight/tomorrow!) But I'm guessing their support won't help with this regardless!

The only other way I can think of doing this is via dedicated hardware and separate vlans right from the main modem? Any recommendations for the modem? I have a couple of Netgear switches which allow vlan segregation etc but have no DHCP servers to serve each vlan

 

 

 

 

View more options
Cynric
12: Established

THG3000 only works with VF as far as I know.

View more options
unclebob1
2: Seeker

So if I go with voda, I'd have two, the second would still be in the same position or will it recognise that the outer one is voda and allow connectivity via wan?

View more options
Cynric
12: Established

If you have this setup

BT Green Cabinet -> THG3000 (192.168.1.1) -> Netgear Router (192.168.0.1) -> LAN

 

Then ...

THG3000 connects to VF and provides a WAN to the second router

Second router does not know about VF and it doesn't care about VF. Second router provides DHCP, WiFi, LAN, and is where the DNS settings are configured. The WAN port of second router is connected to LAN port of THG3000. (EDITED)

View more options
Jayach
16: Advanced member

@Cynric wrote:

If you have this setup

BT Green Cabinet -> THG3000 (192.168.1.1) -> Netgear Router (192.168.0.1) -> LAN

 

Then ...

THG3000 connects to VF and provides a WAN to the second router

Second router does not know about VF and it doesn't care about VF. Second router provides DHCP, WiFi, LAN, and is where the DNS settings are configured. The internet port of second router is connected to WAN port of THG3000.


I don't think that will work, surely it should be a LAN port of the THG3000

View more options
Cynric
12: Established

.@Jayach Haha good spot. Thank you. I have edited.

View more options
unclebob1
2: Seeker

Hold up, so the wan port on thg3000 is an OUT from the thg 3000 to provide a connection to a second router?

View more options
Jayach
16: Advanced member

No, that was a mistake, @Cynric has corrected it.

View more options
Jayach
16: Advanced member

@unclebob1 wrote:

So if I go with voda, I'd have two, the second would still be in the same position or will it recognise that the outer one is voda and allow connectivity via wan?


I have a spare THG3000 router, and have tried to get it to work behind my main THG3000, but no way can I get it to connect to the internet. I think the firmware just won't allow it.

View more options
KeithAlger
16: Advanced member

There are a few possibilities as to why this would be but without the kind of wireshark packet inspection that VF would seem to prefer we not do, it's hard to say for sure.  On top of just the issues from network translating local addresses and VLANs, there is also the possibility that the secondary router is trying to create a PPPoE connection through the primary connection, using either a token or a password/username allocated to another user/line.

 

It's one of the reasons that third party routers even do a better job of Double NAT - there isn't all that additional garbage to deal with!  FYI, Asus routers fair worse than most third-party routers when embedded in a double NAT due to the way they handle the WAN port.

 

*I'm definitely out of my comfort zone on this - feel free to challenge/correct me!

 

 

View more options
Cynric
12: Established

I had just connected my THG3000 to the LAN, now don't laugh but I like a challenge and the setup looks like this (no sniggering at the back):

 

OpenReach -> ZyXel Router -> Netgear Router (192.168.0.1) -> THG3000 (10.0.0.1) -> Laptop

 

Because the THG cannot get PPP (I am not a VF customer any more - you can tell by the huge smile) it will not even pass local traffic to 192.168.0.1, there is something "baked in" with the firmware that wants a direct connection to the VF mothership.

View more options
unclebob1
2: Seeker

Thanks for testing, so it seems that the router is only good enough to extend the WiFi range, with the main router still doing DHCP etc and connected Lan to Lan. I guess the next question (which I believe the answer to is no!) Is there any alternative firmware or is the Vodafone firmware the only option? (Openwrt is not supported)

View more options
Jayach
16: Advanced member
@Cynric wrote:

Because the THG cannot get PPP (I am not a VF customer any more - you can tell by the huge smile) it will not even pass local traffic to 192.168.0.1, there is something "baked in" with the firmware that wants a direct connection to the VF mothership.


In my tests both THG3000's can authenticate to Vodafone if used separately, but can't when connected via the others LAN.


@unclebob1 wrote:

Thanks for testing, so it seems that the router is only good enough to extend the WiFi range, with the main router still doing DHCP etc and connected Lan to Lan. I guess the next question (which I believe the answer to is no!) Is there any alternative firmware or is the Vodafone firmware the only option? (Openwrt is not supported)


You are correct, the answer is no, there is no alternative firmware. (as far as I know)

View more options
Cynric
12: Established

Considering the newly passed "right to repair" law and the existing WEEE regulations about recycling etc etc how on earth can VF get away with the THG3000 not being fully configurable and only fit for a door-stop when you leave VF?

(Mods: perhaps you can find out?)

View more options
unclebob1
2: Seeker

@jayach

  • In my tests both THG3000's can authenticate to Vodafone if used separately, but can't when connected via the others LAN.

Does that imply if I'm with Vodafone I could connect two of these and both would connect successfully to the internet? Would that be both connecting to the phone line or one piggy backed into the other via Lan?

View more options