Connecting 3com Router to Cable Modem

esuki200 · 09-12-2007, 17:08

Hello out there I have recently encoutered the delights of virgin media cable broadband!!! I can connect to the internet using one PC direct to the cable modem router provided but I have purchased a 3com office connect router 3CRWER100-75 and am having major difficulty getting it to work.

Just to go through the basic steps for configuring the router:

1. Select an Internet Addressing mode from the following:
■ PPPoE is required (typically DSL users only)
■ ISP provides configuration dynamically (via DHCP)
■ ISP has provided a static IP address
■ PPTP is required (some DSL users in Europe)

** I select ISP provides DHCP config dynamically

2. Select the ISP provides configuration dynamically (via DHCP) and then
click Next.

** I leave this blank

3. Some ISPs require a host name. If your ISP has this requirement, enter the
host name in the Host Name text box (Figure 18) and click Next. The
Clone MAC Address screen displays.

** I am not sure what is correct here. I can either select not and let the MAC of the router be used or enter the PC MAC or copy the MAC of the Cable MODEM. Any ideas

4.The Router contains a Dynamic Host Configuration (DHCP) server that
can automatically configure the TCP/IP settings of every computer on
your network.

** I enable this so the router creates an IP pool for the computers I want to connect

I dont know if it is something to do with the leasing of the MAC address from virgin do i have to wait for that to expire before the router connection will work??

If anyone can offer me some diffinative help I will be most grateful!! I have had a look at a couple of suggections on here which have been helpful but still havent cracked it. Please any suggestions most welcome

09-12-2007, 17:26

hi

The 'enable DHCP' server & 'obtain an IP automatically' are the correct options.

You shouldn't need to clone your mac for a cable modem, that is only required for using the TV set top box for internet access.

The next important thing is to switch everything off, then turn on the cable modem & let the lights settle until synch & rdy are steady, turn on the router & again give it a chance to initialise, then turn on the PC & you should pick up the connection.

esuki200 · 09-12-2007, 17:58

I shall give that another try......and let you know if it works cheers!!

esuki200 · 09-12-2007, 21:02

Still not getting anything connecting....the router doesnt appear to create any link to the modem any ideas ??

esuki200 · 10-12-2007, 12:41

Would it be an idea to release the IP address from the laptop that can connect to the modem directly ?? Then I might be able to restart the modem and this might allow it to connect ??

is the command ipconfig /release ?

Aragorn · 10-12-2007, 14:44

As long as you are power cycling the modem between connecting/disconnecting the laptop, you should be OK. No need to release anything with IP config.
Can you confirm the cable between modem & router is plugged in to the WAN port on the router? How is the laptop connected to router - via a cable into one of the LAN ports? and you are able to access the router's web page? What IP do you get from the router, eg ipconfig while cabled into router, usually begins 192.168.x.x

esuki200 · 10-12-2007, 15:00

Hello there,

Yes I am powering down the modem and restarting in the correct manner (i.e. modem on -> router on -> and PC on)

Definitely connected into the WAN port of the router from the modem

I have been going from one of the LAN ports into a laptop which can see the router page 192.168.1.1 but the router isnt being recognised by the modem

I just wonder if its something to do with the way that NTL/virigin media supply the IP address doesnt seem to pick up new devices at all as it also fails to pick up my other laptop ???

Aragorn · 10-12-2007, 16:15

Not just one device with problems!
Normally this should not happen!!
What type of modem is it?
With the working laptop, what are the first two octets of the NTL IP, eg 82.6.x.x (Don't post you full IP!)?
What does "IPConfig /all" say about the DHCP lease for that address? Full ouput from that command may be useful (as long as you mask your own IP and the gateway IP)

esuki200 · 10-12-2007, 17:03

Yes that was what i was thinking I didn't anticipate it being that complicated really.

Will have to check when I get in what type of modem it actually is, I know its an ntl type modem

Yes the IP address is something like 86.2.xx.xx

the lease runs for a week which i was surprised about, I was wondering if maybe I need to let that lease expire and then try connecting the router?

Will add some more detail when I find out exactly what type of modem it is

esuki200 · 11-12-2007, 13:43

The Modem type is NTL:250

Aragorn · 11-12-2007, 14:08

Hmm - shouldn't be happening!
The NTL:250 doesn't normally care about MAC addresses and should hand out an IP each time it boots to the first device that asks.
Nope were not missing the obvious - the working laptop isn't using USB is it and if so isn't connected at same time as router?
If not, I would suggest cloning the MAC from the working system on to the router.
ipconfig /all will give you the MAC addr of the laptop Nic, eg 00-17-08-FF-FF-FF, then you can plug that address into the router.
If even that fails, the modem may be faulty. You might be able to get the modem logs on 192.168.100.1 (root/root iirc), but it show nothing.

esuki200 · 11-12-2007, 14:36

I can try cloning the working PC MAC address (I have tried this before but may have fallen down at the patience stage waiting for the modem to kick in)

no its not a usb connected router

If i am getting the internet I would have thought that the modem was working......

This seems to be something that a lot of people struggle with

---------- Post added at 14:36 ---------- Previous post was at 14:20 ----------

I can access the modem on that address on 192.168.100.1 it seems to be working properly but only for that one pc...... you dont think that if i try ipconfig /release that will free up the ip to be allocated elsewhere???

Aragorn · 11-12-2007, 15:27

It 'could' be just the DHCP server that is not working correctly, and if it is doing a release will put you in a worse position as that laptop will also not get an IP!
If cloning doesn't work and there's defo no USB cables plugged into the modem, I would log a fault call.

esuki200 · 11-12-2007, 18:25

Ok one improvement is that I can now access the net through my other PC connected through the modem. Did an Ipconfig /release which seems to reallocate the IP all I have to do now is figure out what is going on with that router!!!! aaaaahhhh the PAIN

esuki200 · 11-12-2007, 23:59

Bizzzzare I have solved the issue and everything is working I booted up the router and plugged in the modem halfway through its startup I know that cant make any difference but i was desperate and it seemed to work.....

Very confused about the whole thing really well a month to setup a wireless router wont go down as one of my greatest IT successes!!

Cheers for the help guys great forum very useful and knowledgeable on the whole!!