Here's the short version: A week ago, all computers on my home network suddenly became unable to browse to websites via http (port 80 was effectively blocked at the modem level). Https (port 443) worked just fine, but anything http would try and connect for a minute and then give me "this page could not be displayed." If I restarted my modem, everything would work great for about 3 minutes, after which I would be unable to use http. After a rough week of trying many different things, spending hours on the phone with Comcast, and even getting technicians out to fix things that needed to be fixed but weren't the source of the problem, the answer ended up being to call 800-COMCAST and ask them to re-flash the firmware on my modem. What, you didn't know about that? Neither did I, and I work in IT. But my friend Grant, who owns an IT company, did. It didn't work right away, but the next morning the problem was gone. On related note, Comcast needs to make its customer service phone systems stop disconnecting people and transferring them to nowhere.
Above is the issue in a nutshell, but if you feel like reading the giant saga of me resolving this problem, it is below. I originally documented everything in case I needed to make a complaint, and in a way it's still a complaint about Comcast's customer service system. I say the system because most of the people I interacted with were great or at least satisfactory, but a lot of weird things happened that required me to call many more times than I would have liked. Anyway, here's the whole thing.
For the first few days after this problem started, I tried everything I could think of on my own, from plugging into the modem directly, to switching from my Netgear router to a Time Capsule, to capturing packets with Wireshark and looking for clues. My friend found a workaround which was to use a free anonymizing proxy that used a port other than 80. It worked but everything was slower, which I didn't like. So I finally give in and call 800-COMCAST.
A woman answers and says "How can I help you?" I say, "I'm having an issue with downstream channel bonding with my cable modem." She says, "Do you mean you have a problem streaming video?" I explain that it's a problem with my modem. She has me do a bunch of stuff like restart it, plug directly into it, etc. Eventually she says I need Level 2 support and gives me a phone number.
I call that number. The guy at Level 2 support is awesome. He quickly scans modem, says the signal isn't right, and schedules a technician to come out the next day, which is Sunday. Perfect.
The technician, who is also awesome, comes out next day, and finds a bad filter and splitter on the telephone pole, as well as one in my garage, which was installed before I moved in and isn't necessary. He fixes or removes all of them. He's super professional, and my internet is 20 megabits faster than it was before! So I'm now getting slightly over 50 Mbit/s (unfortunately, this means I've been getting 30 megabits but paying for 50 for the last two years). Regardless, two hours later, it goes back to the same problem of not being able to access websites via http. Grr!
The following evening, I try calling the Level 2 tech support number I was given two days prior. "Thank you for calling Comcast. This number is no longer in service. Please call 1-800-COMCAST." Weird. Maybe it's to prevent people from calling Level 2 support every time they have an issue?
I call 800-COMCAST and tell them issue wasn't fixed. My agent says I need Level 2 support (good!), gives me the number (different from two days ago) in case I get disconnected. Then she transfers me.
A woman answers, and I tell her my problem. She starts looking up my account, and says "I'm going to put you on hold for a few minutes while I do a test with your modem." After 5 minutes, I hear an automated voice say "Please enter the zipcode where you have or want service," which I recognize as a completely different part of their phone system. What the...? I'm clearly in the wrong place, so I hang up.
I call back at the number they gave me, which I then learn is Xfinity Signature Support. I repeat my problem. She says "I'll transfer you to a technician, but because this isn't a Comcast issue, there will be a charge" I tell her no, it IS a comcast issue because I've ruled out the router. "Ok, I'll transfer you." 2 minutes later: "Please enter the phone number where you have or want service." Again?! Grrr! This time I figure I may as well keep going. I enter my phone number. "We're sorry, Comcast isn't available in your area. If you'd still like to talk with an agent, press 4" I press 4. "Please enter the zipcode where you have or want service." I type my zipcode where I CURRENTLY have service. "We're sorry, Comcast is not available in your zipcode. Please check again later." And it hangs up. This is making me crazy.
I call Xfinity Signature Support again and go through the menus again until I can get a person. I give them my information. They want to put me on hold to run a test on the modem. Not so fast! This time I ask to stay on the line with them, because the last two times I was put on hold, I ended up getting transferred to somewhere random. So he runs the test with me on the line, assuring me that he will resolve my issue. He asks me to type in addresses starting with https (which works) a few times for his tests. Over the next several minutes, I alternate between waiting for a while, then try connecting to a website just using http, which never works. After a while he asks "what browser are you using?" Chrome. "Ok, give me a few minutes" 5 minutes later: "Ok, go to Internet Settings…" I'm on Mac OS. "Ohh, Mac. Ok, give me a few minutes." A few minutes later: "Do you have antivirus software?" No. "Ok. Give me a few minutes." Later: "Do you have Internet Explorer?" No, because I'm on a Mac. "Ok, one minute, one minute-" And then we get disconnected. I checked and the time for this call was over 30 minutes! GRRR!
In total I spent almost two hours on the phone that night and got nowhere.
Two nights later, I decide to try again. I dial the number for Xfinity Signature Support. "Thank you for calling Comcast. Xfinity support has been discontinued as of December 17th." Really?! That was two days ago on the night I called. So I grudgingly call 800-COMCAST, wondering what Level 2 support will be this time.
A woman answers, I explain the situation to her, including that plugging directly into the modem results in the same issue. She asks he brand of my router. I say it's Apple. She says, "Ok, I have to transfer you to the Apple department." I say "Wait, so if I'm plugged directly into my modem and it still doesn't work, who would you transfer me to?" Silence for 20 seconds. "Hello?" I say. "Hi yes, I'm going to transfer you to the Apple department." A minute or so later, she says the Apple department is closed. I say, "I think this isn't a problem with my router, since it keeps happening even if I switch routers and even if I plug directly into my modem. I think this is a Comcast issue. Is there anyone with Comcast who can help me?" She says, "Well yes, since this is out of my scope, I could transfer you to the comcast computer department, since this is a computer issue and not an internet issue." I'm just happy to be transferred, even though I'm pretty sure it's an internet issue, just an uncommon one. After 2 minutes of being on hold, she says "Sorry for the wait, I'm still trying to contact them." This is at 9:45 at night, so I can sort of understand, although it's weird that some parts of comcast support are open late and others aren't. I do appreciate them being open though.
Eventually I get transferred to someone, which ends up being a classic case of "when all you have is a hammer, everything looks like a nail". I explain that I can't browse to any http websites, only https ones, and that I think Comcast must be blocking me on port 80. He says "Ok, go to www.logmein123.com." I try it, and I say "It doesn't work, because I'm not able to access websites via http." He then tells me to find a windows computer and go to www.support.me. I go to my HP laptop and do it, and explain that it's not working because I can't access anything via http. He says "There is a problem with your home network. It is not secure. We need to reset your network." I say "Can we try with my computer plugged directly into the modem? That way we'll know if it's the network or not." He says ok, so I plug my macbook into the modem and restart it. As expected, after 3 minutes, I can no longer browse via http. I tell him this. He says "It doesn't matter whether you are plugged into the modem or plugged into your router, you are still plugged into a network, and hackers can compromise your network. Your network is not secure, we need to reset your network and then secure your network, and-" I interrupt, saying "I really don't think it's my network. I'm an IT administrator, and so is one of my housemates. I'm pretty sure our network is secure." He says "Your network is not secure, we need to reset the network, and then we need to secure the network, and for that there will be a charge." Are you kidding me? I say no thanks, and that I'm pretty sure it's a Comcast issue. He says "Well, there is a number I can give you, and they may be able to help you if it really is a Comcast issue. That number is 800-266-2278," which I recognize as 800-COMCAST. I say thanks and hang up, rather unhappy.
I go upstairs to rant to my friends, and unexpectedly a friend who owns an IT company is over for the evening. He says "Call Comcast, and when they answer, say 'Hi, I want you to re-flash the firmware on your modem' and then give them your MAC address." Skeptical, I call them and say that, and the woman says "Ok, what is your MAC address?" Really? Awesome. I give her the MAC address, and she asks why I want to re-flash it. I explain the issue, and this time I get diagnosed with intermittent internet connectivity. The modem restarts, and the problem is still there. When I log into the modem at 192.168.100.1, the firmware is still "d3000-v302r125532-121212a-L2VPN-CMCST" (Comcast firmware!), so I'm not very confident anything changed. She says to call back if the problem isn't resolved in three hours and they'll schedule a technician to come out. Great! It's 11pm by this time, so I'll just call back in the morning.
The next morning, everything is magically fixed. I don't know if the firmware just takes a few hours to warm up after you flash it, or if Comcast noticed something and fixed it in the background, but I don't care! It's finally working!!!! YES!!
And thus my journey ended. Everyone I spoke to, aside from the last guy, was great and did their jobs well. However, Comcast needs to address the issues with the phone system. They should also put this solution of re-flashing firmware somewhere in their knowledge base in case anyone else runs across it. I'm using a Cisco DPC-3008 modem, if that helps.