Time Capsule with TP LINK MR3420 3G Modem

Question

I am considering buying a IMAC and Time Capsule (TC), one of the reasons would be single vendor backup via Time Machine.
However my present network has a TP Link MR 3420 Router (TP), that handles a modem connection to a 3G Mobile Braodband Dongle.
I wish to keep this.
I have seen alot of discussion about connecting the TC in Bridge Mode, and still allow the TP to handle Network DHCP etc. Whilst this may work, a £249 TC relies on a £ 33 router ?
I have read about putting the TP into DMZ mode, swich off DHCP and foreward the traffic to a DMZ host IP Address.
How can this be configured in reallity, the present TP settings are
Lan IP 192.168.1.1 Mask 255.255.255.000
DHCP 192.168.1.101 to 192.168.1.999 default gateway 192.168.1.1
What are the principal Lan IP address for each device,?? do they both share a common lan address system, or each has a different Lan IP address system.
I would appreciate all help, advice and experiance
John Pierce

Answer 1

You basically cannot have two routers in the network.
Nor can you bridge the 3G router and still pass the IP to the TC.. as indeed most 3G do not allow that kind of setup.
You need the TC to have extensions to plug 3G wireless USB modem .. we will wait until doomsday before that happens.
Since you have to be dependent on a £ 30 router to control my home network so be it..
The actually ability of the router is not necessarily a big issue. The router in the TC is actually nothing particularly wonderful and the TP-Link will have a lot more ability.
Unless you run into some major issue I would just stick with the TC in bridge.
You can double NAT.. use DMZ as you suggest.
The problem here is that you are still totally dependent on the TP-Link NAT.. and you have added a second NAT to make it worse.
It is possible to setup the TC in a transparent mode where it is functional as dhcp but not double NAT.. this of course does make the TC appear as if it is the main router.. but it is appearence only.. the TP-Link is still the main router.
See https://discussions.apple.com/message/22695632?ac_cid=tw123456#22695632
For this method which is designed to avoid the DNS of the TP-Link more than what you are trying to achieve but the effect might do what you want.. Do not use DMZ.. or if you do, use the end computer IP which should be accessible to the TP link as the TC is not actually forwarding.