Cable Modem Won't Play Nice with Wi-Fi Router

I ran into an issue today where I attempted to connect a wi-fi router to an existing (working) Motorola cable modem. Although the Internet access worked fine when the cable modem was directly connected to a PC, hooking up the router allowed only Home Group connections; no Internet access.

I tried two different routers (a Linksys WRT54G and a D-Link DIR-615) - same problem. I turned off Windows 7 firewall - no luck. 45 minutes on the phone with TVMax (the service provider's) techs resulted in conflicting answers on if the cable modem is the culprit.

The phone tech first did a ping test on the modem; it came back at 100%. We checked ipconfig and network settings on both the wired and wireless PCs; everything was in order. Using a different Ethernet cable did not solve the issue.

Level 2 tech support had me unplug the Ethernet cable from the modem while leaving the power on. The modem's "activity" light continued to blink. Based on this, the level 2 tech declared it a modem failure issue (even though the modem works perfectly when connected to a single wired PC).

When I go through the steps of unplugging the modem, hooking the modem to the router, a router port to the PC, powering on the router then reconnecting the power to the cable modem, the results are:

• Power, signal, send & receive lights on modem: solid green
• Activity light on modem: flickering yellow
• Status light on wi-fi router blinks green
• Internet connection light on router is solid green
• Connection to wired port (PC): solid green

Has anyone else experienced a similar issue - and, if so, did it turn out to be a problem with the cable modem? I don't want to spend time and money buying a new modem for the client and spending half an hour on hold waiting to register the new MAC address only to find out a new modem doesn't solve the problem.

 

I've been running a Motorola surfboard modem and Linksys WRT54G since June 2004.
First make all the cable and ethernet connections but do not plug in the power bricks to the modem and router yet.
1. Plug the power brick to the modem in. Watch until all 4 upper lights are solid green.
2. When the top 4 lights: power, receive, send and online are green and the PC activity light is flashing amber, Plug in the power brick to the router. The power light and the WLAN lights should be solid green. Depending upon which port you plugged the computer into, one of the lights 1, 2 3, or 4 should be solid green and the Internet light will be flashing green.

If you open a command prompt (Start/Run type in cmd) and type in ipconfig /all
what do you get?

Footnote: I'm using my 2nd Motorola because tech support told me my fisrt modem was probably bad. It was not. After I hooked up the new modem, I still had the same problem. It turned out to be a weak signal. I now have a spare cable modem as a backup, in case this one dies.

 

Just wanted to 2nd plodr's suggestion. The normal way to power up is modem first, once it's ready then power on router then computer last. If you do the router before the modem they may not sync up.

Sam

 

Thanks for the tips. Since the router had a guided setup CD, I followed the steps exactly as outlined. I also tried rebooting the wired PC and using the reset button on the router before a second install attempt. No luck.

Today I hooked up another router (same make/model) to a Scientific Atlanta cable modem at my dad's church without a hitch.

Based on the time I spent on the issue with the cable company's tech support, my friend was able to beat down the cost of a new modem through the cable company to $30. Once the MAC ID has been registered and confirmed on the replacement modem I'll try again.

 

When you have the cable modem connected to the router it is plugged into the WAN port, correct?
The router giving out IP addresses?
Log in to the router (gateway address) 192.168.1.1 (or like) and look for the WAN IP and see if your router is getting an IP from the cable modem.

Post findings.

 

The router reset button only returns the router to default settings (default username and password - things like that), it has nothing to do with resetting a connection. I just wanted to be sure you are clear on that.

If the power goes off, I generally have to power down my router (not reset button, actual removal of power brick plug) and print server to get everything talking to each other again.

 

My friend had the cable modem replaced today. After he did a wired connect to the PC to verify the MAC ID had been registered and the Internet was working, he called me and I tried again.

The problem is still there: The Internet signal will not pass through the router into either a wired or wireless PC, even if the router ie set up as an unsecured network. :banghead

At the risk of too much information, here are all the steps I went through on two attempts with two different wi-fi routers (a Linksys WRT54G and a Fry's FR-300RTR <same chipset as D-Link DIR-615>):

Prior to attempting setup I:

• Disconnected the Enhernet cable from the modem to verify the "activity" light went off with the Ethernet cable disconnected (on the old modem, the activity light stayed on even with the Ethernet cable disconnetced; this was TVMax's previous diagnosis of a defective cable modem causing the problem).
• Powered up each router (no Ethernet cables connected) and used the reset button to clear any previous settings and restore it to factory defaults. Once the front panel lights indicated it was reset I unplugged it.

For the setup of the Fry's router, I ran the setup CD. In step one (PC connected to the cable modem without the router) the setup software verified a good connection to the ISP. I followed the next steps exactly as listed:

• Disconnect power from modem.
• Remove Ethernet cable from modem; reinsert into port 1 of router (router to PC).
• Power up router.

The software recognizes the router and does the initial configuration. I verified this by entering the address of 192.168.0.1 into IE8 and was able to see the router setup screen.

Finally I connected an Ethernet cable from the modem to the router Internet port and powered up the modem. Although the Internet light on the modem is solid green, neither the setup software nor Windows network troubleshooting recognizes the Internet connection. The network map shows an active connection to the router, but a red "X" between the router and Internet. The only possible flag is that the router's "status" light blinks once the cable modem is powered on.

For the attempt with the Linksys, I skipped the setup CD but followed the setup order noted above. Entering the Linksys router address of 192.168.1.1 I was again able to access the router setup. The only difference in the results from Windows Network Troubleshooter is it gave a "DNS Error" message asking me to contact the network administrator.

Back to square one: The Internet service works with a direct wired connection to one PC but won't pass through a router. TVMax swears they use DHCP and no special router settings are required.

What am I missing here? I have set up three of the FR-300RTR routers on Comcast ISP in the past month with no issues whatsover. Although the WRT-54G is an older model router, I have set up several over the years using both cable and DSL with no issues. The odds of two different routers being defective with an identical issue are astronomical. In addition, Windows Device Manager shows the network adapters on both the wired and wireless PCs as working properly.

I'm thinking it has to be an adjustment to the router's advanced settings for it to play nice with the TVMax modem - but what specific setting? Level 2 TVMax tech support said no router adjustments were required.

FYI, TVMax is a cable company that services apartment complexes. If anyone has a magic bullet that might solve the problem, thanks in advance for posting it.

 

Did you happen to get this working?