Can I configure 5GHz for mixed mode like DDWRT?

Hi guys,

I am going to give you guys a little background on what I need to accomplish so you guys will get a better understanding why I am asking if there is a 5Ghz mixed mode like DDWRT. I have Comcast as my ISP. I have been having severe problems with my cable internet. I am getting a severe noise issue that is causing low SNR on one downstream channel using 591Mhz channel. When I first plug my modem in all my downstream channels SNR is about 42db except the 591 which is 36db. Then, after a random amount of time it drops below the cutoff for Docsis 3.1 which is 33db and I get disconnect and a bunch of uncorrectable codewords and critical even log errors. Comcast has ran all new lines, but cannot seam to resolve the problem. I told them maintenance needs to come and track down the source of the noise. I have an appointment in the morning for 8am to 10am. So hopefully this will all be resolved.

Now onto why I ned mixed mode for 5Ghz. I am working from home right now and need internet, I read and article that I found through Google one time about a guy using OpenWRT to increase his Comcast speeds through dual WAN by using in cable internet and a Comcast xfinitywifi hotspot. I would like to do that same so if my modem disconnects I will still be connected to wifi which will serve my 2.4Mhz and 5Ghz networks internet. The reason I need mixed mode is because I have varying 5Ghz devices. Then, I would like to use 5Ghz AC to supply the bandwidth from the xfinitywifi to my router so I can get the fastest speeds the access point will give me. I do not want it to be bottlenecked if that makes sense. Is this possible? If so how can I go about doing something like this? I need you guys bad. I am losing days of work over this =( Thanks a million fellas!

xfinitywifi comes from the cable modem so if the modem disconnects xfinitywifi won't help you.

Customer rented modems do not broadcast the xfinitywifi hotspots. Only Comcast rented equipment. However, if you rent a Comcast device you can disable it from the xfi app. Therefore my modem is not broadcasting a xfinitywifi. I have access to any of the networks names xfinitywifi, XFINITY, or CABLEWIFI. As you can see I have a lot of options.

  • xfinitywifi - will likely not suit your needs (since it's not prioritized, and it's unencrypted); but I don't understand why you can't connect to it (you just hit the "Join Network" button - the captive portal authentication may be another struggle)
  • XFINITY - will not work with routers [1]
  • CABLEWIFI - don't see one listed; but nonetheless, on a web search, the instructions I find lead me to the the same directions on how to connect to XFINITY, so it won't work either

Is your coax plant grounded to the unified house ground?

Ummmmm...I understand what you meant, but this statement (or your math) is incorrect. If your numbers as posted are accurate, it seems you'd be blaming the other channels...or perhaps you meant "signal" and not "signal-to-noise-ratio"?

:confused: No, I don't see that...unless you didn't realize you need a key (i.e. its passphrase) to access them (and for XFININTY a cert bundle they only install thru thru app :wink:) ...and since most are hidden, their SSID too. Lastly, I'm not sure why you haven't already connected to xfinitywifi already. Is that causing you an issue?

[1] Unless you can figure out the issue the OP in the other post has regarding certificates. :bulb:

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The mwan3 package allows load balancing or failover between multiple WAN connections.

It seems likely your neighbors have similar signal problems. You could set up a single WAN connection through the neighbors as a test. Using the encrypted connection requires EAP authentication with your Comcast credentials. EAP requires replacing wpad-basic with a full version such as wpad.

591 MHz is used by over the air TV (RF channel 34). Is there a TV transmitter nearby?

Because the request is to be a client and AP on the same radio. He's "losing days of work" due to not running the AP on 2.4 and client on 5 because of his desire "not to be bottlenecked if that makes sense."

Yes, and the OP also said:

I think you forgot the "fastest speeds" part - the theme to which my response to the OP remarks. Nonetheless, I'm not clear why you reiterated that to me.

Nonetheless, I see no reason they cannot connect...the OP can ask if they need some other config to make it work...or something is missing (I assumed since a 5.4 scan was done, that's what they want to connect to).

Also there may be "lots of neighbors" but the strongest one is -80 dBm which is not going to be fast or reliable. The RF situation needs to be improved.

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RF and plant/site coax...something is definitely wrong in the OP's area with RF.

I wonder if the OP happens to live near or in an area with a permit to jam RF...? (common near bases, airports, radio telescopes...etc. - or just living around those areas)

I was talking about the strength of the 5 GHz wifi signal from the neighbors' Comcast boxes that he intends to mooch from. A CPE would be useful there, or at least identify the target and move the router to a window facing them.

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Fastest speeds means clients connect to router by 5Ghz and router connects to xfinitywifi by 5Ghz with a single radio. They're not asking to connect to xfinitywifi. They're asking how to do like the "guy using OpenWRT to increase his Comcast speeds through dual WAN by using in cable internet and a Comcast xfinitywifi hotspot" but with a single radio and using the neighbors xfinitywifi instead of their own.


(Did you actually proofread your statements?) the OP wants dual WAN to an AP that's not xfinitywifi - yet showed a screenshot of Comcast APs???

Sure sounded like they want to connect to an Comcast AP to me. Nonetheless, I guess you didn't read my thread, or you think "double-explaining" will make me give a different response?

If your statement is accurate, then you should probably ask the OP to explain what AP they actually want to connect to, as their post says:

I already posted that the OP needs a key for other encrypted APs anyways, so again, I don't get why you're repeating things. As I noted, maybe let the OP respond if they need to.

Why do you keep repeating this?

(Yea, just let the OP respond).

Or a directional antenna (technically, this is only legal if the router already allows you to unscrew the antennas).

I was able to use a range extender that I had before to do this. I think it was a Netgear 6300. It looked like a router. It had like 4 or 5 Lan ports and two antennas. I was able to give all my devices wifi using it. Therefore, I do not see why I cannot do the same again? Except this time shoot the signal back to my router and have it use the connection like a dual wan setup. This is exactly what the guy did in the article I was reading. Here is the link

Also, the numbers I posted are correct about my modem. The SNR for downstream for a cable modem should be higher that 36db but can be as low as 33db. However, below 33db and you will have problems I will leave the link at the bottom for your reading pleasure. My router is connecting to channelid 19 which is 591mhz. On that channel I my SNR is fluctuating. Sometimes it is as high as 36db. However, it goes below 33db a lot as low as 26db I have saw it. When it does this it causes tons of uncorrectable codewords and event log errors. I will leave screenshots for your reading pleasure as well.

Now onto not being able to connect all of my 5ghz wifi devices when I was using AC mode and 80 width in openwrt. All I had to do was set openwrt to use a channel that all my devices would support. I actually found that there are two channels that are broke with openwrt. When chosen they set the channel to a different number than it should be. So I lose two compatible channels for my devices due to these channels not working correctly. The problematic channels were 44 and 48 I believe. I know it was two of the lower channels from 36 to 48. Anywho two of those channels do not set to the right channel when selected.

For your reading pleasure.

Sorry mk24, the part about creating a WAN through my neighbors is over my head. I am trying to understand as it sounds very interesting but with my limited knowledge of this kind of stuff I do not fallow fully. Sorry about that.

As far as the noise someone on the dslreports forum said the same thing. This was their exact reply.

That is right around broadcast RF channel 33-34. It looks like WFMJ broadcasts on RF 33 (their on-screen channel is 21). It could be interference from that, although the transmitter is about 17-20 miles away.

I have not seen anything out of the ordinary and now that all my cabling has been replaced from the modem to the pole with brand new wiring, connectors, and ground blocks I know it is not something simple like a cracked cable shielding on my end. Whatever it is has to be getting into the cable companies wiring somewhere. I do not see any transmitters anywhere nearby.

Because not all my devices have wifi connections. The only one being my laptop and my Roku sticks. Not my work desktop. So I need a range extender or AP to pass the signal along to my router which is located in my office which I am using openwrt on. The only place I get a good signal is on the outside wall of my kitchen or living room. I do not want my work desktop in either of those areas. I know realize now my router would not be able to do both. Serve a connection to my wifi devices as well as connect to wifi and use it for bonding the two connections together like I read in the article or as a backup WAN connection. This would require a separate device.

This signal was not measure at its optimal location.

There is a very small airport maybe 5 to 10 miles west of me. There are no bases or radio telescopes that I am aware of.

Technically I do not know if it is a neighbors modem that he is renting from Comcast or a real wifi device from Comcast. However, paying for Comcast service. I can use any device named xfinitywifi or XFINITY wifi completely free of charge. Due to the fact I am paying for Comcast services. Comcast hosts these wifi hotspots from clients modems. They are completely separate traffic. Therefore, no stealing from the neighbor.

lleachi is correct. It would not be mooching. These hotspots are hosted from modems that customers rent from Comcast in which Comcast hosts a separate wireless network from the customer rented modem to increase Comcasts wifi coverage. Anyone who pays for Comcast cable services or that purchases a wifi pass can legally use these hotspots. No stealing involved :wink:

Well, dang! I thought it was leaving my comments under each person comment they posted. Sorry if I did this wrong :sob:

So now that I have thought about things it is going to take some type of wireless device mounted to the outside facing wall in my living room or kitchen to connect to a Comcast hotspot. Then, send that signal to my router with OpenWRT. From there it can be used as a dual WAN to increase speeds and to be used as a failover. That way if I get disconnected from my Comcast cable connection due to this interference I will still have the xfinitywifi feeding all my devices because some do not have wifi cards.

So at this point I just need to know which device should I purchase for this task? Also, how would I go about setting up openwrt on the router to get it to accept the connection?