View Full Version : Need Help with Mediacom Cable Modem Setup

01-07-2003, 12:19 AM
Hi All,
I have just had to switch cable modem service providers (from Roadrunner to Mediacom). Roadrunner was very straightforward - I just had my Linksys cable Router connected to the modem and everything just worked fine. DHCP was set on both WAN and LAN sides.

Now with Mediacom I can't get the system to work with a router. When I do the initial setup, I am connected directly from my mac to the modem. Mediacom registers the MAC address of my computer and then it works fine. But then if I try connecting the router in-between I get nothing. Their network is DHCP and I have the correct settings on the router.

What should happen when I connect via the router for the first time is that they will note a different MAC address (from the router rather than my mac) and will ask me if I want to switch to this MAC address as my accessing device (they only allow one). But I can't even get that far.

I also tried using the MAC address cloning capability of the router to emulate the MAC address of my computer - but no change - it still doesn't work.

I was once able to get to the point where it registered the MAC address of my router, but then what followed was the most unbelievable slow performance ever seen from a cable modem - like being connected on an old 2400 bps phone modem. Then it didn't work at all.

Mediacom won't help - as long as it works with my mac connected directly to the modem, then they say that its a router problem (and thats my problem!). I tried upgrading the firmware on the router but to no avail. I then tried dropping in a brand new Linksys router, but the performance was exactly the same.

Can anyone shed any light?? The modem is a Motorola Surfboard, and the Router is a Linksys BERSF11.

Thanks ..... Taffy.C

01-07-2003, 09:35 AM
I went from DSL to mediacom last month. They had a special https IP for the registration process which required using secure web proxy setting. There was some trouble and we registered the cable modem (my own, new Motorola SB4200, which is great modem), and the router. There was one other problem later that came up, with Mac OS, you will need to put the primary and secondary IP DNS Server address into the router and/or System Preferences.

If they won't register both MAC addresses (router and cable modem), keep talking and ask to take it up another level. Also, I asked *repeatedly* for the DSN Server IP and they wouldn't provide it. Finally when talking to someone who knew and liked the Mac OS (he was planning to install Jaguar soon, like when 10.3 comes out), he said, "oh, with Mac you HAVE TO HAVE DNS IPs."

I have read a lot of messages on the net when I went DSL, I use to use MLPPP, and when it came to choosing a router, as good as Linksys is, I also think sometimes there are either very easy to use and configure, or difficult and a pain. plus the method for upgrading firmware (and sometimes having to downgrade)... so personally I went with Farallon and Netgear equipment. Old Mac equipment makers.

When you initially setup, you should have done it with the router connected I fear.

01-07-2003, 11:24 AM
Thanks. I did start with the router connected when I initially tried to register the service. But there was just no connectivity. The Mediacom tech support guy said that he could see that there was "something" connected to the modem but that it wasn't communicating.

When I hooked up the mac directly to the modem, that worked just fine, and there were no dns or domain names when I looked in the network control panel. So, I'm a bit confused about why I would need the primary and secondary DNS addresses when I didn't have those set on the directly-connected mac??

In any case, can you share those with me??

I guess I think that the Linksys router is doing something weird - probably need to spend some time on the phone with them tonight.

Thanks ... Taffy.C

01-07-2003, 11:56 AM
Without the IP numbers, you will run into trouble with resolving domain name's and be unable to resolve domain NAME into IP NUMBERS. Maybe later today or tomorrow, but seems to affect Macs, and happened day (or two?) after installing and setup. Putting the numbers into that field is "optional" and this has nothing to do with being 'directly connected.' It has to do with being unable to resolve "cnn.com" into its IP number address. In fact, not having a router might make it essential to have that field - and it won't get filled in automatically.

I assume that you were told to use Internet Explorer and to select "Secure Proxy" there rather than using the System Preference "Network" (under Jaguar) to make the initial setup.

When I had DSL they weren't as concerned with MAC address and I could use Router or computer. With cable they seem to try to implement more controls (and feedback as there is a lot of behind the scenes 'communication' between my Mac and their servers, on bootup and at other times).

Using cable, you really need a router for its firewall and NAT support, and maybe firewall on your Mac. If just using modem and your Mac, and running Jaguar, definitely want firewall (Brickhouse or built-in but something). You are always on and your system will be pinged, probed, and could end up being used for peer filesharing w/o your knowledge or consent).

Even though I have DHCP, the router gets the same IP every time, even if the modem is off over-night. Which is almost like static IP, and I wish that I didn't.

01-08-2003, 10:33 AM
I've spent about 5 hours on the phone now with both Mediacom and Linksys. the Mediacom support guy was very helpful and actually was somewhat mac-savvy - knew what jaguar was! What we figured by the end of his call was that for some reason the Linksys router(s) are taking forever (more than an hour in some cases) to pull down an IP address from the mediacom server. When you connect a mac or PC directly to the cable modem, they obtain an address immediately. Also, once the router obtains an IP address it is still basically non-functional - still can't get websites to load, can't access email, etc.

He then passed me up the food chain to a Level 2 support specialist who turned out to be very rude and unhelpful - told me that it was my problem - something wrong with my router. I told her that it was the same problem with both of my linksys routers, but she wasn't interested in helping at all.

I then spent a long time on the phone with Linksys tech support - I was pretty happy with the level of dedication and service. They were familiar with Mediacom and knew all the correct server ID's and DNS addresses, etc. So, we spent quite a while trying almost every configuration possibility on the router. Initially they thought it could be an IP-address conflict between the router and the Motorola modem (which they said also uses an IP address range in the 192.168 series) but that didn't fix the problem which continues to be that the router is just not easily obtaining an IP address from the server. Linksys have now escalated this to their level 2 support and say they will get back to me ......

I called Mediacom again and asked if there are any routers which they know will work OK with their network. They said they have had no problems with Linksys, D-Link, and Netgear working straight out of the box.

I wonder now if there is maybe some weird conflict between the router and the Motorola 4220 cable Modem. I know that Mediacom has only started using those recently.

Think I might go pick up another brand of router too just in case. The only thing that keeps me going now is the anticipation of that great feeling when you finally solve a big problem!

01-08-2003, 12:24 PM
I just did some experimenting on my own using two routers. I use my old router which Mediacom has the MAC address for and handles the cable modem (SB4200), along with DHCP. Then use a routing table to go from there to a new Netgear which Mediacom doesn't see, doesn't have the MAC address.

The second router handles all the local hub traffic and also acts as DNS Server to three Macs.

There is a place in your Linksys to manually put the DNS IP numbers rather than in your Mac's control panel.

The Netgear is not really better, but it has a very easy to use Setup Wizard and onscreen help so you have the "manual" right in front of you telling you about each field. And it will attempt to autoconfigure which seemed to work right.

The only reason I went back to my original router is that I'm busy, would need to access the secure Mediacom proxy server and/or talk to someone on the phone.

The Motorola modem you have I didn't see when looking, just the SB4100 (discontinued) and the replacement SB4200. I assume 4220 is a variation.

Have you logged into the router? changed the password from default, which is often something terribly obvious like blank or 'password' and configured for DHCP, not to use PPPoE and inserted those IP numbers?

01-08-2003, 03:34 PM
Still waiting to hear back from Linksys. Gregory, there is something I don't get though - when I connect a mac or a win2K PC directly to the motorola modem I have no problem pulling an IP address from the Mediacom DHCP server. But when I put the router in line, it can't find an IP address. Isn't the DHCP process the same regardless of whether the modem is connected to a pc or a router??

01-08-2003, 04:44 PM
The router's MAC address needs to be registered. When you first setup service, you didn't have the router. When you talked on the phone, they should have added the router's MAC hardware address.

01-08-2003, 11:30 PM
It is registered - they did that over the phone for me. They can see its there - just that it won't pull an IP address

01-09-2003, 12:19 AM
YIKES!!!! It works - I picked up a D-Link Router, took it out of the box, did absolutely no setup, connected it to the cable modem, connected to the mediacom website, and registered the new mac address. The router obtained an IP address immediately and I am now happily surfing the web!

Not sure what the issue was with the 2 Linksys routers, but I suspect that there must be some compatability problem with the Motorola cable modem.

Now I'm going to take back both the D-Link and the Linksys routers and pick up a new D-Link 614 with the Wireless Access Point included. Now I can get on to setting up the wireless part of my network.

There is a God!

Thanks for all your help Gregory.

01-10-2003, 06:09 PM
I have now replaced my router with the D-Link 614+ which combines the Router with a 4-port switch and 802.11b wireless access point. It works very well - I have it in my basement and have good wireless performance right through my house.

I have not heard back from Linksys yet on why their router didn't work.

One last question before I throw the box away - in future I will want to be able to remotely access two of the macs on my home network from the public IP network. The macs in question are connected to the router by wired connections. Are there any special considerations I need to be aware of in the features of the router to be able to support this??

Thanks Taffy.C

01-13-2003, 01:22 PM
You need to access the Macs how? Which protocols? ssh for remote login (and scp for file-transfer)?

If you've firewalled the internal net so that there's only one IP address routable on the outside Internet, you can set up specific ports on the router that get forwarded to (other) specific ports on internal hosts. It's *usually* safest to have just one internal host accessible from the outside, per protocol anyhow. For example, you can forward port 22 on the outside of the router to forward to one of your Mac's port 22 on the inside and enable ssh (secure remote login shell). At that point, you can ssh to *that* host from the outside, then bounce a second time from it to any other host on your internal net. Except for global services like your web-server, you'll usually want to specify in the router which specific outside IP addresses should be allowed through service ports like ssh.

There are services you should generally avoid exposing outside -- file-sharing is a biggie -- unless you *really* know what you're doing and how to contain the dangers. Even then, the risks can be high.


01-14-2003, 11:24 AM
MacIntouch reader (Safari thread): <BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Date: Mon, 13 Jan 2003 11:26:56 -0500
From: Randall Meadows
Subject: Safari Reader report: RE: Safari and Linksys Router

I too all-too-often have my LinkSys Cable/DSL box freeze up, and not just with Safari. It sometimes seems to have problems passing large amounts of data for a prolonged amount of time, but not most of the time, just occasionally. Cycling the power on the box clears up the traffic jam.

For me, it seems to happen most when I set something going, then walk away to let it finish. http://macgurus.com/infopop/emoticons/icon_frown.gif <HR></BLOCKQUOTE>
'nuf of these type comments and I almost got D-Link, and definitely avoided Linksys. That said, while Netgear works, I have yet to be able to update the firmware (won't expand or work on Mac) OR to hear back from their tech support in a WEEK!

01-04-2005, 07:04 PM
I seem to be having the same or very similar problems. Using my QS 733 10.3.6 connecting via Built-in Ethernet using DHCP - I started by just putting the new modem where the old one was ... figured it would just go.

phone/cable jack -> modem -> router -> computer/s

A new cable setup today with Bresnan as the ISP and a Motorola SB5100 modem - if connected directly to the modem no problems. The computer retrieves an IP Address, Subnet Mask and Router number. The numbers are much different than old provider. I access the internet just fine.

I put my LinkSys BEFSR41 back into the picture and the computer sees the router fine and displays a IP Address, Subnet Mask and Router number. Just as always - same numbers. But will not get to internet.

The new modem Motorola SB5100 and old router LinkSys BEFSR41 seem to not be talking or recognizing each other. I am going to back up again and start fresh.

Any suggestions would be appreciated. I will have both my DSL and cable for a month or so. - a freebie - plus I need time to swap email issues and such.


01-05-2005, 05:23 AM
My cable ISP at one point changed their setup to register the MAC address of the router as well as the modem. And I am/was mediacom.

Also, 10.3.6/7 - you may need to manually put primary and secondary DNS values into OS X Network pref, even though they are handled by router.

I have the same modem but went back to DSL. If I were doing it today, I would do Netgear cable modem with built-in router/switch in one unit.

Also, there was a lot of tips on www.dslreports.com FAQ on cable modems, grounding, UPS surge protection to protect your modem - a lot.

01-05-2005, 01:54 PM
I had to re configure the router. It was a simple fix so hopefully no more problems. I never do this stuff on a regular basis - so it seems real foggy.

Thanks for all there tips TZ.