Solving Double NAT with Time Capsule + BT Home Hub

Question

Solving Double NAT with Time Capsule + BT Home Hub

CONTEXT

I am using a new Time Capsule with a BT Home Hub4. I have switched off the wireless capacity of the Home Hub, and am able to use the Time Capsule's wireless network for internet access and Time Machine backup.

PROBLEM

The Time Capsule light flashes amber, and Airport Utility shows 1 problem:

'Double NAT'

Any thoughts on which settings need to change:

- in the Home Hub ?

- in the Time Capsule ? t

to eliminate this error message ?

(I am aware that Bridge Mode is a simpler possibility, but I am reluctant to use the (less capable) Home Hub wireless network and disable the Time Capsule's ).

Many thanks for giving this some thought ...

OS X Yosemite (10.10.3)

Posted on Apr 24, 2015 4:51 PM

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Answer 1

Best reply

Bob Timmons

Community+ 2024

Level 10

159,164 points

Apr 24, 2015 5:05 PM in response to compositeFunction

You are trying to run two NAT routers on your network.....that is why you see the Double NAT message.

You might have turned off the wireless on the HomeHub, but it is still operating as a wired router delivering DHCP and NAT services for the network.

The Time Capsule is trying to do the same thing. You do not want two devices both trying to act as routers on same the network. That is a network no no.

To fix the issue......

On your Mac.....open Finder > Applications > Utilities > AirPort Utility

Click on the Time Capsule icon, then click Edit in the smaller window that appears

Click the Network tab at the top of the window

Change the Router Mode setting from DHCP and NAT to read "Off (Bridge Mode)"

Click Update at the lower right of the window

Wait a minute for the Time Capsule to restart with a green light. Viola.....no more Double NAT and the Time Capsule will still be providing your wireless.

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Answer 2

Apr 25, 2015 1:06 AM in response to Bob Timmons

Thanks !

Would it be possible to use the Time Capsule,

rather than the BT HomeHub4,

as the router ?

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Answer 3

Apr 25, 2015 2:09 AM in response to compositeFunction

No, the HomeHub is modem or if not it is usually working with VDSL where the login details are not revealed.

The TC is not a modem.. so it has to plug into a modem..

Why do you need the TC to work as router? It is nothing special on the router side.

You can use a different method if you want to control the network from the TC.. this is fairly involved in needing to set static IP..

See details here.

https://discussions.apple.com/thread/5981989?answerId=25135547022#25135547022&ac_cid=tw123456#

I use this setup for particular reasons.. to avoid my ISP DNS ..

But for most people it has really little to offer it above bridge.

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Answer 4

Apr 25, 2015 5:55 AM in response to compositeFunction

Would it be possible to use the Time Capsule,

rather than the BT HomeHub4,

as the router ?

You might be able to remove the BT HomeHub and replace it with a special modem like the Draytek Vigor 120. Then, the Time Capsule could be set up to operate as the router on your network. More info here:

Vigor 120 ADSL Modem - Draytek

You would want to check with both Draytek Vigor and BT to make sure that this would work before you buy the modem, of course.

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