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Posts: 1
Registered: ‎09-10-2007

Subnet Mask

Hello, I am currently running my WRT54g router on my university network of which I am assigned a static IP with the university. The subnet mask they provide the residents with is and I was wondering if I would be able to setup my router to use the same subnet mask ( rather then the very few limited options available in the drop down box under Network Setup section on the web admin interface. My Router Version is 8.0 with the latest official firmware.
Posts: 12,649
Registered: ‎07-16-2006

Re: Subnet Mask

You can use any subnet mask you like on the WAN side. That is where you have to set your static IP address and subnet mask.

You can use only subnet mask or smaller on the LAN side for your own LAN. There is usually no need to change that unless the network on the WAN side overlaps with the default subnet of the Linksys router. In that case you have to change the LAN IP address of the router outside the WAN side subnet.
Posts: 7
Registered: ‎09-14-2007

Re: Subnet Mask

[ Edited ]
Hi im Damien im having similer problem
First can you tell me what a
IP, Subnet Mask, DNS, and Defalt gateway is for and uses my computer says im connected but i can't accsess the internet mabe the problem is on the linksys setting i left the DNS and Defalt Gateway Blank, i put the ip adress i found on my PC and subnet mask then it said i was connected but i can't get on the internet
Please help me out with problem Thanks
(Mod Note: Removed Email address.)

Message Edited by daikunzeon on 09-14-2007 08:18 AM
Posts: 10
Registered: ‎09-06-2006

Re: Subnet Mask

This is still not clear. I have mt WRT300N bridged across a Netcomm Nb5 ADSL2+ Modem Router. Why is it bridged? So I avoid double natting, which upsets VOIP. The problem - I cant get to the NB5 to see it's status, unless I disconect a PC and conenct directly to it, (disconnecting the WRT300N. The NB5 is at I have set up the WRT at, and wanted a network mask of so that anything inside the range of to was acceptable. i.e. was the only .1.x, and from any of the .2.x systems, I should be able to open up the status pages on the modem. Please explain how I can do this...
Posts: 12,649
Registered: ‎07-16-2006

Re: Subnet Mask

You can't. It is a limitation of those cheap routers.

1. With the modem in bridged mode the router does PPPoE. Thus the primary internet connection goes through the PPP tunnel.

2. The IP address of the modem is "outside" this connection. What you would need is a way to send a IP packet directly to the WAN port. This, however, cannot be configured on these routers. The router simply uses the remote end of the PPPoE tunnel as default gateway and will send everything there.

3. Changing the LAN subnet mask on the router won't make any difference. The modem is connected on the WAN port, i.e. not in the LAN. If you would set the subnet mask to on the LAN port the router will consider the IP address of the modem as LAN address and thus forward the packets back into the LAN. With that setting packets will not even cross the router.

4. Thus, the easiest way to get access to the modem is to unplug the router temporarily and connect a computer directly. Alternatives would be to buy a professional router like a Cisco, see whether you can installed some 3rd party firmware like dd-wrt on your wrt300n, which would allow you to set up the necessary routing, or to buy a switch, connect modem, WAN port of the router and a LAN port of the router. Your computer requires a static route for to send it directly into the LAN instead of using the default gateway. It may be possible to setup this route on the router as well.