Help: Small school in need, No internet access over lan

[Iceshot]

Ok Networking guru's, need some help here. Helping (volunteering) with a small local charter school dealing with their IT needs.

School's Router went bad (Linksys EA2700) and I'm attempting to get them back up and running online.

Here's the Setup:

Charter Business Cable Internet (Static IP, MUST be hardcoded into router as modem is restricted from pushing the settings out via DHCP. Verified this myself)

Modem : SMCD3GN2 Modem (verified internal firewall and wireless are turned off)

Router : Asus RT-N66U (rev B1) (Firmware 3.0.0.4.270 *unmodded*) (Static IP hardcoded)

Network Traffic Map: Modem ---> Router ---> 3com 48 port switch ---> Local PC's

No internet access to any connected device wired or wireless. Issue appears to be strictly DNS related. For example, if I enter Charter's DNS info into windows tcp/ip bam I get internet access. Remove the DNS info from windows tcp/ip and set DNS to auto = lose internet access. I want the router to handle this automatically for all connected clients.

The router is delegating dhcp assigned IP's in the specified address range to all clients no problem, just no internet. Bypassing the switch going directly into the router makes no difference, same problem. What am I overlooking here?

Will be back in the morning to continue working on this. Advice is greatly appreciated, Thanks Guys!

 

[Demo24]

Make sure DNS in the router is set properly, technically you could use another DNS service (like 8.8.8.8) if you wanted.

I've found Charter quite easy to work with and those SMC modems tend to work quite well (never been in the interface), long as it is properly doing IP-passthrough (which it sounds like it is) its really just a matter of putting the right numbers in the right spot.

 

[Cooky]

It sounds like you forgot to put in the DNS IP's in the DHCP server portion of the router configuration.
From a windows PC, if you do a "ipconfig /all", do you see the DNS entries?
If not, that's your problem.

Download the manual from:
http://www.asus.com/Networking/RTN66U/#support_Download_30

Look for the FULL manual (third one from bottom), titled "ASUS RT-N66U B1 user's manual for English".

In p38, you'll see a screenshot of the DHCP config.
Make sure you key in the DNS server in there.

 

[Iceshot]

It sounds like you forgot to put in the DNS IP's in the DHCP server portion of the router configuration.
From a windows PC, if you do a "ipconfig /all", do you see the DNS entries?
If not, that's your problem.

Download the manual from:
http://www.asus.com/Networking/RTN66U/#support_Download_30

Look for the FULL manual (third one from bottom), titled "ASUS RT-N66U B1 user's manual for English".

In p38, you'll see a screenshot of the DHCP config.
Make sure you key in the DNS server in there.

Thanks Cooky. I wont be able to verify until the morning, but im fairly certain I've covered this. Im remember DNS field only allowing you to enter one DNS address (no secondary). The default gateway I assume is the one assigned by the ISP correct?

 

[Cooky]

No - default gateway in the DHCP setting is the IP of the router, facing client side.
If your client IP subnet is 192.168.0.0/24, and you assigned the router 192.168.0.1, then the default gateway should be set to 192.168.0.1.
It's used to instruct the PC's which device to talk to, in order to reach the Internet.

This may be the issue then.