anyone know about cable modems and routers?

[Melgamatic 66]

Location: Fanwood, NJ 07023

Service: Comcast HSI with Blast!

 

My old setup was:

 

Linksys BEFCMU10 modem -> Linksys WRT310N router -> Netgear GS116 switch -> 3 Mac computers, tivo, etc.

 

After realizing my speeds were lower than expected with Blast! (I was getting 5.1Mbps down), I called Comcast service.

 

Of course we setup the direct connection for the phone call:

 

Linksys BEFCMU10 Modem -> Macbook

 

The phone tech had me check the speed, got the 5.1Mbps. He checked my modem remotely and found no problems. He rebooted it, with no change in speed. He is stumped, because everything seems ok to him.

 

The guy tells me that my "old" modem may be the problem.

 

He schedules a tech visit.

 

----

 

Technician comes today (2 hours early). Checks the signal up to the modem, tells me that everything is perfect, signal levels are great, etc., and then leaves. He said "maybe it's the modem."

 

So, I'm stuck with still slow download speeds (5.1Mbps), no more help from Comcast.

 

----

 

We drive over to BestBuy and buy a new Motorola SB6120 modem. Here is the info:

 

Model Name: SB6120

Vendor Name: Motorola

Firmware Name: SB6120-1.0.2.1-SCM00-NOSH

Boot Version: PSPU-Boot 1.0.0.4m1

Hardware Version: 3.0

Serial Number: 317001928809794605030011

Firmware Build Time: Jul 20 2009 20:04:47

 

So, I setup the direct connection:

 

Motorola SB6120 -> Macbook

 

Speed is great, around 23.5 Mbps down / 4.6Mbps up!!

 

A few minutes later, I start getting all my web pages redirected to:

 

http://actsvr.comcastonline.com/nocache/realactsvr.html

 

(I could ping any website by name during this time

[coldsolderjoint 84]

What do you want to be the DHCP server? Doesn't the Surfboard default to be the DHCP server?

 

Is DHCP turned on with the linksys router?

 

When we got FiOs, I tried using my Linksys Router as a switch, defaulted everything, turned off wireless and turned off dhcp.. the default setting said to pick up an ip from DHCP.. it didn't happen. It stayed at 192.168.1.1. So I manually set it to an unused IP and it everything worked.

 

I once set up a a network with verizon DSL. A tech said he didn't know why.. but he always had to set the second router to 192.168.2.1. (So the cable between the modem and the second router was 192.168.1.0 and the rest of the stuff was on 192.168.2.0). Didn't really make sense.. but I tried it and it worked.

 

Or.. do you have any old settings left in the network settings of the main computer? Did you try disabling and re-enabling the NIC? Maybe restart the box?

[Melgamatic 66]

What do you want to be the DHCP server? Doesn't the Surfboard default to be the DHCP server?

 

Is DHCP turned on with the linksys router?

 

You *should* be able to have both setup for DHCP, the router getting it's address dynamically from the modem, and then everything connected to the router automatically gets its address from the router's DHCP. The modem isn't going to do the NAT'ing for me...

 

How is the NAT'ing going to work if the DHCP is in the modem?

 

Hm....

[Melgamatic 66]

Further research on the intertubes seem to indicate that the SB6120 modem's DHCP is only activated when the modem is disconnected from the internet.

[coldsolderjoint 84]

What do you want to be the DHCP server? Doesn't the Surfboard default to be the DHCP server?

 

Is DHCP turned on with the linksys router?

 

You *should* be able to have both setup for DHCP, the router getting it's address dynamically from the modem, and then everything connected to the router automatically gets its address from the router's DHCP. The modem isn't going to do the NAT'ing for me...

 

How is the NAT'ing going to work if the DHCP is in the modem?

 

Hm....

 

But.. the router and modem have to be on one network.. and everything connected to the router has to be on a different network. Otherwise the Two DHCP servers are going to conflict. No?

[coldsolderjoint 84]

Further research on the intertubes seem to indicate that the SB6120 modem's DHCP is only activated when the modem is disconnected from the internet.

 

So does the router have a valid ip address?

[crazyboy 13]

Do the other computers on the network direct you too that page or just the one? Reset router?

[Radek 73]

If the modem supports DHCP, turn it off. (You may have to connect a laptop to it directly to access its admin interface, independent of any other devices. It probably has a web interface for admin.)

 

Use the router as the single DHCP server and NAT device in the chain. (btw. If router supports VLAN (multiple LANs), you could do some funky setup (only if needed.) Also, the switch may support VLAN ... ignore that for the moment.)

 

When you say Phone is connected directly (I assume you mean VOIP), do you mean connected directly to the router or to the modem? I assume the modem has a single LAN (side) port, if so how is the phone directly connected? Or a phone via macbook? Keep that for last to figure out ...

 

I run VOIP off of my comcast setup, but it's completely NAT'ed by the router, i.e., non-public IP 192.168.x.x.

 

Suggest you use the following:

New Modem -> Router -> Switch -> macbook(s)

 

Use the new modem, until you diagnose the networking setup. If the previous modem was really old, it might need a firmware upgrade to support the higher blast speeds (or some setting might limit it), or it could simply be a setup problem. Dunno.

 

In this setup, Router is going to support DHCP (for wired and wireless connections) and NAT.

 

The switch will simply give you additional wired connection ports; this will provide the DHCP issued (by router) IP addresses to connected devices.

 

On the macbook, disable/enable/reset the net interface and/or find/issue the command to reset the DNS cache. I am not a mac guy, so can't help you without research.

 

This should give you clean slate on the macbook, then try to connect.

 

Hope this helps.

[Malsua 1,422]

Check the router status page, it is showing that it got setup correctly from the network, with the same IP address as my computer got before, good subnet mask, DNS server names, etc. It is cloning my computers mac address. So, it appears to be working correctly.

 

If the WAN IP on the router is a routeable IP address (i.e. NOT 192.x.x.x, 169.x.x.x, 10.x.x.x) then the router is set up correctly. Can you ping www.google.com?

 

It sounds to me like DNS isn't properly flushed. Switch the router's DNS to the OpenDNS servers 208.67.222.222 and 208.67.220.220 and see if that makes any difference. You could also just enter those DNS servers in each machine to see if it makes a difference.

[Caine 147]

I only skimmed this, and this may not be relevant at all, but why are you having the router clone your main PCs mac address? I've never had to do that with Verizon (FIOS) or Time Warner (Road Runner)... Unless comcast has some whacky mac filtering policies, as long as the mac from the modem is registered with their network, none of the other mac addresses should matter. Again, may not be related, but it stood out in my mind when i skimmed your post.

[Melgamatic 66]

Thanks everyone, the problem was resolved.

 

I had mac cloning on because a million years ago all the broadband providers required it, since they only allowed you to hook up "one" device; that's changed over the past 5+ years, but it never hurt anything.

 

The problem was that I never did a full "hard reset" on the router, which includes power cycling while holding down a tiny red button on the back panel for more than 30 seconds. Once done, everything worked.

 

Thanks, Dave