Router and network help

[Trumple]

Hey guys,
I'm trying to setup my wireless router to work at University halls. It's a standard modem router, D-Link if that's any help
Each room has one ethernet port in the wall, which connects to the university LAN, which lets us access the internet.
I did a little searching and found I should turn off the DHCP server feature on the router, and set the subnet mask to the same as the mask supplied by the LAN. I also set the IP of the router to a B class IP (152....) which is within the DHCP range of the university DHCP server. 152 is a public IP which means each computer has it's own public IP (that's just how the university "LAN" works). I also set the DNS servers in the router config to the DNS servers of the University

Now, when I first turn it on, it all works perfectly. It will work for a while, then suddenly it will all fall apart. I would be able to access the config page through the IP I set on the config page, but any computers connected to the router will not have internet access.

I get the feeling I need to set the IP of the router to one OUTSIDE the DHCP range of the university server. Problem is, I don't want to set an invalid IP for the router. I don't really know how subnetting works, so I don't know what IP address I can even set the router to so that it will be inside the range of the subnet and outside the DHCP range.

LAN subnet provided by university network: 255.255.255.128
Fact worth noting: the "internal" IP on the LAN is actually an external IP (the university has its own ISP) so I'm not sure how this will affect it.

Very confused here, not quite sure how to fix this intermittent problem. Should I give the router a private IP? (192....) Does it need to have the same subnet? What does the "128" on the end of the subnet mask mean?

Thanks for any help!

[dbk21894]

Turn DHCP back on, and connect the router like you would at home. There is no reason that you should have to change any settings.

[Drumdevil]

Why do you use a modem router to connect to your LAN?
There is probaly a security that kicks in when you try to connect devices like that.
You should connect a simple network switch.
Not being able to connect to the internet is maybe because you need to setup a proxy.

[Trumple]

Thanks for the replies guys, I've now got a little further.

So if I leave the settings at default, I cannot access the router config when I plug it into the socket. If I set it to have some IP that makes it on the same subnet as I, it all works.
However, it's temperamental, and after a few hours I think it gets assigned some other IP. Anyone know how to find the other IP? I've tried tracert, wireshark, nothing seems to show it's existence

Thanks again

[dbk21894]

If you plug the WAN port into the Uni's network, then connect yourself to the router via the LAN ports or WiFi, then you should get a local address separate from the Uni's network. To find the router's IP just look for the router address in the network connection details dialog.

[Trumple]

[QUOTE=dbk21894;34309144]If you plug the WAN port into the Uni's network, then connect yourself to the router via the LAN ports or WiFi, then you should get a local address separate from the Uni's network. To find the router's IP just look for the router address in the network connection details dialog.[/QUOTE]

That's the current setup, which works if I DON'T get a local IP (if I do, I cannot access WAN)
As for getting the IP of the router, it does not list it IP in the details. It lists the gateway (Uni gateway), some DNS servers and the DHCP server (again of the Uni)

Thanks anyway

[Zah]

Actually, try leaving the default settings but connect the network to one of the LAN ports instead of the WAN port. This worked for a consulting group that was trying to plug a wireless router into the facility's network where I used to work (as IT).

[Metalcastr]

Yeah that should just make it a switch. Also turn off DHCP so it doesn't try to assign ip addresses to other network nodes. That was a huge problem at my university a few years ago.

[Trumple]

[QUOTE=Metalcastr;34336254]Yeah that should just make it a switch. Also turn off DHCP so it doesn't try to assign ip addresses to other network nodes. That was a huge problem at my university a few years ago.[/QUOTE]

Yup I've done that.

Basically my problem is the router gets assigned an IP after a while, and I don't know what that IP is.
I can get connected to the WAN through it, so now it's just a case of "what is the Ip of the router"

Looking through basic connection info, the gateway, DHCP servers, DNS servers etc. all point to Uni equipment. It's as though it ignores the router completely

So I tried tracert, wireshark, even checking the arp cache, nothing would show the IP of my router sitting next to me!
So far, I've given up and accepted the fact that if I want to change any setting on the router I'll need to reset it and re-configure completely.
If anyone has any other ideas, they would be appreciated

Thanks!

[Metalcastr]

It should tell you the IP in the router's settings page. Just log in and view it.

[Trumple]

[QUOTE=Metalcastr;34353054]It should tell you the IP in the router's settings page. Just log in and view it.[/QUOTE]

Wait what?
You need the router's IP to actually log in in the first place :v:
I'm saying I don't even know what its LAN IP is

[Zah]

[QUOTE=Trumple;34355562]Wait what?
You need the router's IP to actually log in in the first place :v:
I'm saying I don't even know what its LAN IP is[/QUOTE]

So, you can access the university's network through it then, just not the router config? You may have to disconnect the router and perform a reset on it to get the original settings. Make what changes you want, then hook it back up.