Solution 1 - Disable the second router
Updated September 28, 2005
The easiest way around this whole problem is to not use the second router as a router! After all, it's the NAT firewall that's causing these hassles, and if you don't need it, don't use it!
The only times you really need the second router to act as a router are:
- If you intentionally want to create a protected part of your LAN via the second router's firewall
- You want to combine the firewall features of both routers, i.e. port filtering, content filtering, logging, etc.
If you're not trying to accomplish either of the above, then you're better off disabling the second router. Here's how:
1) Choose a LAN computer on the second router and statically set its IP address information to their current values (use the Support tab of the Local area Connection Status window on WinXP and 2000, and Start > Run > winipcfg on Win95 and 98 systems to grab the current IP address info). This will keep the computer that you'll be using for the next steps from losing its IP address info and the ability to connect to the routers.
NOTE: Ignore this step if the computer you choose already has static IP information, and remember to change back to "Obtain an IP address automatically" if you weren't using a static IP setup.
2) Turn off the DHCP server in the second router. The first router also has a DHCP server, and you don't want the two to conflict when you connect them.
3) Change the address of the second router so that it's in the same subnet as the first router and doesn't conflict with the first router's base IP address or DHCP server range. This will ensure that you can reach the admin server of the second router from any LAN machine.
For our example setup, the first router base address is 192.168.1.1 with DHCP server range of 192.168.1.100 to 192.168.1.150. So set the second router base address to any IP address between 192.168.1.151 to 192.168.1.254
NOTE: Once you make this change, the computer you're using will no longer be able to communicate with either router because it is set to an IP address in the subnet you just got rid of. So go back into the computer's TCP/IP properties and change it back to "Obtain an IP address automatically" (and do a DHCP release / renew) or set its IP address info statically.
4) Once you take care of the items above, connect a LAN uplink port on one router and a LAN normal port on the other. It doesn't matter which you use on which router, but don't use the Uplink ports on both routers! If neither router has an uplink port, just use a crossover cable to connect any LAN port on one box to any LAN port on the other. Figure 2 shows an example of the two interconnection schemes when one router has an uplink port.
Figure 2: Router interconnection
Note that since you're no longer using the routing part of the second router, none of the WAN (or Internet) setup parameters matter. You can just leave them as they are... they won't affect anything.
Congratulations! You've just turned that second router into a dumb switch and/or access point, and your sharing troubles are over!