Starting a week and half ago my router stopped working with my cable modem. I went to sleep with it working and woke up with it not. I swapped in another router and am still having issues; I was gone for 10 days so now I'm back to trying to figure it out. While I was gone I left everything (cable modem, router, and computer) powered off.
My setup:
- Comcast Ambit cable modem (from Comcast)
- Netgear WGR614 v4 router –> replaced with Linksys WRT54GS v1.1
- Windows XP SP3
- other computers, all currently unplugged
- The modem is using the firmware (ver 2.105.2001) provided by Comcast; hardware version 1.3
- The Linksys router is using FW ver 4.71.4 (latest for this release of HW), factory defaults
- I am only using the wired connections; no wireless.
- I have swapped out all of the cat5 cable.
- The router is cloning the MAC address of my PC (according to Comcast, this is not needed)
If I plug my computer directly into the cable modem, I can ping by name or number. Everything works perfectly.
If I plug my computer into the router and the router into the modem, I cannot access anything outside of my local network. This is the exact setup I've used for the past 5 years; there were no changes in the past year.
Now here's the interesting part: I can log into the Linksys router and get status information from it; everything appears good. Using the Diagnostics, I can run ping and traceroute to any site on the internet. These work perfectly. From my computer, I can ping the router and the modem. However, I cannot ping anything on the internet by with name or number. If I plug in another computer, I can ping it successfully.
I've included two transcripts below that show these two attempts. Addresses, DNS, gateways, etc. look good. I cannot access the internet through either router.
I am at a loss here. Suggestions? Help!
Computer to Router to Cable Modem
C:\>ipconfig /renew
Windows IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : hsd1.ca.comcast.net.
IP Address. . . . . . . . . . . . : 192.168.1.100
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
C:\>ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : wynton
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : hsd1.ca.comcast.net.
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : hsd1.ca.comcast.net.
Description . . . . . . . . . . . : Intel(R) 82562V-2 10/100 Network Connection
Physical Address. . . . . . . . . : 00-1D-09-9B-45-EB
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.100
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DNS Servers . . . . . . . . . . . : 68.87.76.178
68.87.78.130
Lease Obtained. . . . . . . . . . : Monday, March 22, 2010 10:21:55 PM
Lease Expires . . . . . . . . . . : Tuesday, March 23, 2010 10:21:55 PM
C:\>ping google.com
Ping request could not find host google.com. Please check the name and try again
.
C:\>ping 74.125.19.104
Pinging 74.125.19.104 with 32 bytes of data:
Request timed out.
[...snip 3 more failures...]
Ping statistics for 74.125.19.104:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
C:\>route print
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 1d 09 9b 45 eb ...... Intel(R) 82562V-2 10/100 Network Connection - Pa
cket Scheduler Miniport
0x10004 ...00 0a 3a 6f 68 41 ...... Bluetooth LAN Access Server Driver - Packet
Scheduler Miniport
===========================================================================
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.100 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
169.254.0.0 255.255.0.0 192.168.1.100 192.168.1.100 20
192.168.1.0 255.255.255.0 192.168.1.100 192.168.1.100 20
192.168.1.100 255.255.255.255 127.0.0.1 127.0.0.1 20
192.168.1.255 255.255.255.255 192.168.1.100 192.168.1.100 20
224.0.0.0 240.0.0.0 192.168.1.100 192.168.1.100 20
255.255.255.255 255.255.255.255 192.168.1.100 192.168.1.100 1
255.255.255.255 255.255.255.255 192.168.1.100 10004 1
Default Gateway: 192.168.1.1
===========================================================================
Persistent Routes:
None
C:\>
Computer to Cable Modem Directly
C:\>ipconfig /renew
Windows IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : hsd1.ca.comcast.net.
IP Address. . . . . . . . . . . . : 71.204.149.195
Subnet Mask . . . . . . . . . . . : 255.255.252.0
Default Gateway . . . . . . . . . : 71.204.148.1
C:\>ipconfig /all
Windows IP Configuration
Host Name . . . . . . . . . . . . : wynton
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : hsd1.ca.comcast.net.
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : hsd1.ca.comcast.net.
Description . . . . . . . . . . . : Intel(R) 82562V-2 10/100 Network Connection
Physical Address. . . . . . . . . : 00-1D-09-9B-45-EB
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 71.204.149.195
Subnet Mask . . . . . . . . . . . : 255.255.252.0
Default Gateway . . . . . . . . . : 71.204.148.1
DHCP Server . . . . . . . . . . . : 68.87.76.10
DNS Servers . . . . . . . . . . . : 68.87.76.178
68.87.78.130
Lease Obtained. . . . . . . . . . : Monday, March 22, 2010 10:18:50 PM
Lease Expires . . . . . . . . . . : Monday, March 22, 2010 11:12:31 PM
C:\>ping google.com
Pinging google.com [74.125.19.99] with 32 bytes of data:
Reply from 74.125.19.99: bytes=32 time=20ms TTL=55
[...snip 3 more success...]
Ping statistics for 74.125.19.99:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 17ms, Maximum = 28ms, Average = 20ms
C:\>ping 74.125.19.104
Pinging 74.125.19.104 with 32 bytes of data:
Reply from 74.125.19.104: bytes=32 time=18ms TTL=55
[...snip 3 more success...]
Ping statistics for 74.125.19.104:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 16ms, Maximum = 18ms, Average = 17ms
C:\>route print
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 1d 09 9b 45 eb ...... Intel(R) 82562V-2 10/100 Network Connection - Packet Scheduler Miniport
0x10004 ...00 0a 3a 6f 68 41 ...... Bluetooth LAN Access Server Driver - Packet
Scheduler Miniport
===========================================================================
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 71.204.148.1 71.204.149.195 20
71.204.148.0 255.255.252.0 71.204.149.195 71.204.149.195 20
71.204.149.195 255.255.255.255 127.0.0.1 127.0.0.1 20
71.255.255.255 255.255.255.255 71.204.149.195 71.204.149.195 20
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
169.254.0.0 255.255.0.0 71.204.149.195 71.204.149.195 20
224.0.0.0 240.0.0.0 71.204.149.195 71.204.149.195 20
255.255.255.255 255.255.255.255 71.204.149.195 71.204.149.195 1
255.255.255.255 255.255.255.255 71.204.149.195 10004 1
Default Gateway: 71.204.148.1
===========================================================================
Persistent Routes:
None
Best Answer
I'm thinking that things were good until your ISP changed your IP address, gateway, or DNS servers recently. Check your computer's host file. Could you have some ancient settings in there that are blocking things? Also, could you have some obsolete firewall settings?
Also, make sure that your ISP is giving you valid DNS server addresses, and that you are using them. The ones in your listing don't work for me, but I think it's just because I'm not on comcast.
But, if they don't work from Comcast, maybe they are obsolete.
So, do
nslookup www.google.com
and see what your get. Then try
nslookup www.google.com 192.168.1.1
this will be asking your router instead of the external DNS servers.
Added this:
It seems obvious, but check that things are cabled up right. Is the cable modem connected to the WAN port of the router? It should be. Is the computer connected to a normal LAN port -- not designated as a monitor port or something?
I suggest that if you don't need to be doing MAC Address cloning, that you turn that off. It could be causing a weird problem.
If I was your ISP, and I wanted to create this situation, (say I didn't want you to use a router, or I wanted to force you to buy my router), I would make sure that all inbound IP traffic coming out of your cable modem had TTL (time to live) of 1. Any such traffic would be (correctly) dropped by the first router it hit. Your outbound traffic would still work, but you just couldn't get anything back. This would be an underhanded trick, and I've never heard of anyone doing it, but it would exactly explain your symptoms.
Check to see if the PC and the router can ping their default gateways. This should be the easiest thing to get working. Then see if the PC can ping the external gateway (the one the router sees).