All of my 2.4G devices are no longer able to connect to gateway. Recent change or failure?

I had the same problem last month after changing old modem to Xfi.  It broadcast the network as 5ghz.  I had to go into the modem settings and create a 2.4 ghz network. The same name and same password (or can be any name and password, I guess if you want it different) There are some post showing you how.  I am far from an expert and don't work for Comcast.   Since no one has offered any help yet, I decided to let you know what I did. 

thanks for the tip. sounds reasonable. especially since nothing else I've tried over the past few days has worked. Was about to carry the gateway back to the store. I'll try this first.

I felt like I left you hanging nowhere to go. I dug around and found this ...

https://www.xfinity.com/support/articles/change-wifi-admin-tool-xfinity-xfi

It show you how to open the  Gateway tool and change the setting and how to cretate a 2.4 ghz band . You alway had the band , it just doesn't broadcast..   My wife is disabled and I am not far off.  So we have several smart bulbs, plug and device that operate through Alexa  in which we depend. and mostly work only 2.4 ghz. 1986 they put a computer on my desk , they  said it would make my  job easier. Play with it, I could hurt it. The next morning they had to restore the state server.  They paid for me to take some courses.  What I lack in computer literacy, I more than make up in guts and stupidity.  While this  seems  a bit risky, it is pretty straight forward.  If you mess up, i think you can restore to default.  If not just tell them it is broke... 🙂  But you should see you  network as 5ghz and another as 2.4.  Another option I suppose is you could connect to xfinitywifi which is basically a open connection to your Xfi gateway used for guest and not secure.  Good Luck

I too have the exact same issue that just started a few days ago.  I talked with Xfinity Support and they thought I was nuts.  I have some Kasa Smart Plugs and some Samsung Smart Cams that work on 2.4G only and they all quit working.  Trying to reconnect, none show my network which makes me believe the 2.4G isn't working any longer even though it shows both 2.4 and 5 are both enabled.  I have inSSIDer software that looks at WiFi networks that are in range and mine does NOT show.  I tried Disabling 5G on the modem and none of my devices saw my network including phones, PC's, iPad, and all the 2.4G devices.  As soon as I Enabled 5G only the devices that support 5G saw and connected.  There's obviously something going on with Xfinity such as modem software or firmware update they recently performed since several of you are seeing the exact same issue in the same timeframe!

I'm wondering if some versions of the modem hardware/firmware are not compatible with new firmware being flashed or software upgrade.

I logged into my modem and went to the Troubleshooting tab, then selected WiFi Spectrum Analyzer.  It did it's scan and 5G is the only thing logged, 2.4G wasn't even recognized.  I'm guessing that isn't normal if both 2.4G & 5G are both enabled.  I also tried giving the 2.4G a different name than the 5G and that didn't change anything either.  Xfinity is sending a Tech out but I think it's a waste of time as this happened suddenly a few days ago and everything had been working fine for months.  Dollars to dougnuts they are going to recommend swapping the modem out.  That said, it would be interesting to know the exact cause.

Seattle_Mike, hmmm, that is very peculiar. Thanks for taking the time to post on this thread. Is bandsteering enabled in your modem? If the 5.0 Ghz frequency is the strongest, then your devices will connect to that one while the 2.4 Ghz waits to be steered as the primary frequency. If you're using a mesh network, the 5.0 Ghz frequency is favored so the best bet is to use a 2.4 Ghz router to connect those devices. 

Ken

Thanks for the posts and replies. I work in IT in my "day job" and am relatively familiar with networking, although admitedly not an expert on the Xfinity WAP. After attempting everything that I could think of or was advised to do over a week, I finally simply returned the device to my local Xfinity store and received an immeidate replacement. After setup, it worked great with all devices once again connecting and visible as original. Ultimately, I'm left to conclude some type of hardware or firmware failure related to the 2.4G radio. Advice: save the frustration. Get a replacement. Much faster and easier.

RJS3, swapping is also a viable option! Thanks for posting your solution!

Thanks for the posts and replies. I work in IT in my "day job" and am relatively familiar with networking, although admitedly not an expert on the Xfinity WAP. After attempting everything that I could think of or was advised to do over a week, I finally simply returned the device to my local Xfinity store and received an immeidate replacement. After setup, it worked great with all devices once again connecting and visible as original. Ultimately, I'm left to conclude some type of hardware or firmware failure related to the 2.4G radio. Advice: save the frustration. Get a replacement. Much faster and easier.

Seattle_Mike, glad you were able to separate the bands. I think you may be right about the modem swap. Let us know how the visit goes. 

Ken

Even after the band seperation, I was still having issues with lost connections on WiFi . I am connected to the Xfi by ethernet or even as I am only a room away (maybe 25 feet away), I couldn't connect at 5 ghz, and the 2.4 was spotty. I have a older house (paid for) that used sheet insulation with foil layers. I decided to invest in the pods which seem to eliminate most of the issues. In fact the modem is in the very corner of the house. If that didn't work I was considering investing in a little coaxial cable and moving it at least to the center. The cable line was placed years ago..long before I decided I needed all the gizmos I now have. The placement wasn’t very good to broadcast. So I wanted to mention this along with everything else as a possible solution.

I'm less than 6 feet away from the modem while doing testing!... 5G signal is full scale no matter where I'm at on my 1 acre property.  The signal is simply just not there, period.  If it was a signal issue why did everything work great for the last year or more?

Problem resolved by changing out the modem.  Both the Service Technician that came out & Xfinity Tech Support line were very professional & courteous.  It still seems this happening to quite a few people and in the same short period of time says it's likely not just a "coincidence".  Something likely happened from a remote upload of s/w or firmware that messed with the 2.4G side of the modems. Not that unusual to run into compatibility issues and I feel better it wasn't anything on my end that could of prevented it. Close the book on this one, at least for me.  Thanks again to Xfinity for the great support!

It could be a Washington software thing.  If you are  around Seattle , I am just a bit south of you.  So maybe I should trade mine as well...

Could be... they did NOT charge me to send a guy out & he had a new modem in the truck so it saved me a trip to the Xfinity store.  You might want to confirm the "no charge" thing before asking for someone to come out.  Here's something you can do to verify if your 2.4 is really not working.  Log in to your modem, go down to Troubleshooting and Select WiFi Spectrum Analyzer.  It will run through a scan and product a report.  BOTH 5GHZ and 2.4GHZ should show up.  With my old modem ONLY 5GHZ was reported which verified 2.4 wasn't working at all.  Hope this helps others.