Changing Comcast Modem/Router to Bridge to Airport Extreme

Unfortunately, you may have to face the fact that a modem/router or gateway device may not be capable of operating as a simple bridge mode modem. The fact that you might see a setting for Bridge Mode does not necessarily mean that it will do what you need.

Comcast cannot change your modem/router or gateway to Bridge Mode....you have to have a tech come out and configure your device onsite....or you might be able to do this yourself.

The big questions are:

1) Whether your modem/router can even possibly be configured to operate as a bridge mode modem. If you have it set for "Bridge Mode" now, and things don't work....you likely already have your answer.

2) Whether Comcast will support this type of connection, even if it is possible

Having tried this with some modem/routers in the past....for many hours.....I would say that life will be tons easier if you can get Comast to swap out the modem/router for a simple modem. Or, if you have to buy a modem yourself, ask Comcast for a compatible model that will work with their service.

I had similar issue recently. Xfinity sent me a new model which was actually a wifi router as well. And I have Airport extreme base station. Instead of setting the Xfinity router to bridge mode I just set the Airport extreme base station as a bridge mode and connected the AE WAN cable to a LAN output of Xfinity router. With AE in bridge mode , I was able to add 2 additional Airport Express and extend my n/w, as well as use airplay.

One -ve with this approach is that Airport Extreme in the bridge mode did not support a guest network. I have two wi-fi network now , one from Airport Extreme and the other one from Xfinity router. I just use one of them as guest n/w.

Second issue with this is that there is one extra n/w hop . But AE is connected to Xfinity router using Gigabit LAN so latency is negligible .

The 3rd issue with this apporach is that the device names doesn't show up in the Airport Utility. You can only see the MAC address and the IP instead of actual device name. It is a minor irritant for me.

In my experience, if you call Comcast and make the request they will remotely login to the modem and throw it into bridge mode for you so you can use The Apple Airport Extreme as your primary router. I've done this to, at least, 4 different comcast (now Xfinity) devices as their wifi router stink. Half of them out there that have been at sites for a long time don't even run Wifi N. Heck I had a client with a NEW wifi device from comcast and it was not Wifi N capable. Ridiculous. It should only take you 10 mins on the phone with the RIGHT tech to get this done. There is no reason to run your Apple Extreme in Bridge.

Since you have an SMC device, it sounds like you have a business class circuit. However, if getting a tech on the phone has them scratching their head at what "bridge mode" is, I doubt that's the case as business class techs would know what you need to do. The SMC needs to be set in bridge mode and then, since you have a static IP, you simply enter the IP, Subnet, and Gateway address into the Apple Extreme under Internet. You'll have to drop the selection down to "Static" to set these addresses manually. In my experience with the SMC routers, they have DHCP on by default so it should hand off an IP to your Apple Extreme. To login to those SMC routers given out by Comcasr the username is - cusadmin and the password is - highspeed - this will give you the ability to set DHCP and configure port forwarding and such if you need to. The bad thing is, only their "Admin" login can set it to bridge mode so that's why it has to be done over the phone and they do this remotely. Last, as about 1.5 months ago, they have phased out that SMC Networks modem / router for the new Docsis 3.0 unit. It can grab 10x the speed as the SMC. I called Comcast and they sent a tech out to swap out my modem. I was pulling 16MBPs down and now I'm bursting to 62MBPs down. Comcast, of course, isn't going to offer this info so you need to rattle an account reps cage about the age of your router and the speed of your line. They only charged me $10 more a month for that kind of speed due to the extra cost of the modem. They rolled a 3rd party tech to my site to plug up the new modem and I had him throw that into bridge. That SMC is old news and slow....talk to a sales rep about your account and get some more speed off that circuit. Coax is capable of 100+MBPs down using the Docsis 3.0 modem / router.

Comcast have finally fixed this issue and added a bridge mode switch in the Admin page of the comcast router.

Just type in 10.0.0.1 enter admin/password for the login and on the first page there is a button to flip on Bridge mode.

Flip the switch, let the modem reset, plug in your Airport Extreme into port 1 of the back of the comcast modem and fire it up.

Let everything stabilize and go into your Airport Express application and put your router into DHCP and NAT mode

Setup your static IP's the way you want.

You will manually have to input DNS servers of your choice. I use OpenDNS but any DNS server you like will work here.

Comcast DNS Servers

Safe and update your Airport Extreme.

Let everything come back online and you should be good to go.

My wireless speeds are now back to where they were prior to getting this new Comcast modem.