Unusually high data usage megathread

I am having the exact same problem. It has been increasing over the last few months, and now I am over their cap. Before pandemic, I averaged 400GB. After pandemic, it went to around 700GB, which I would expect from working from home. But it has been increaseing to just under my cap for the last couple of months, and now I went from 90% to 100% usage in just 48 hours, with something like 60GB per day. One of those days was a saturday while no one was home and all electronics were off. I would basically need to be watching two HD streams 24/7, including while I'm asleep. I have been monitoring the traffic through my router and it only comes up with about 1/10th of what comcast is stating. I would believe that my router's monitoring might be a bit off, but I can't imagine the difference being that extreme. I'm going to continue monitoring it myself and if this issue doesn't seem to go away then something with their equipment must be faulty. We just had a big storm that knocked out their service across the whole city for around 24 hours, so maybe that is the case.

Our data usage was averaging around 600 gigs up until December of last year, when it suddenly shot up to 1200. We're not using any additional devices, nothing's changed, but in January we went over 1.2 terabytes. Considering that xfinity says 1.2 terabytes is sufficient for about 95% of users, it seems strange that we'd be using so much data. We're not twitch streamers or anything, I'm a Salesforce admin who works from home, my partner works at the office.

Last month I changed our internet password thinking that maybe someone was using our internet unauthorized, but we're halfway through the month and already used over 900 gigs.

I'll upgrade to the higher package if that's what I need to do, but it just seems fishy so I wanted to check beforehand with those that may know better than I. Thanks in advance!

@ashmateja Scroll back through the thread for various ways of tracking your data.  There are a lot of variables depending on what you have and how "technical" you want to get.  I would guess that in the last year, more than 5% have been going over, but even using the 5% number, that’s more than 1.5 million customers. I have a pretty good idea where the data is going here and can tell without looking at the meter when a month is going to come in high or low.  Other people have gone for years without thinking about it, so it may all seem like a mysterious mess at first.

We have been Xfinity customers for the last year and a half and just recently started receiving notifications that we are going over our data limit.  We are 16 days into February and just got a notification that we've almost hit the terabyte limit.  We have been working from home since March due to the pandemic and not changed our daily practices yet somehow these last two months have seen us doubling our data usage according the Xfinity.  The other weird thing is that Xfinity no longer has any data on our usage prior to November so I can't even look back at what our average usage was.  I can say that in November we used 453 gb of data.  In January we supposedly used 1950 gb of data with literally zero difference in our day to day.  How does that happen?  Is Xfinity broken?  Where is our past month usage information, Xfinity??

I really need help here guys.

Xfinity internet usage is showing me I have already consume 1200+ GB of internet but my router is showing me cleary only 580+ GB as you can see in this picture.

Internet usage 

I`m tired of paying every month extra $$$ for this and pretty sure I have not used that amount ,xfinity is doing something wrong annd they refuse to help me, what can I do ?

Had this issue months ago - personally, I feel Comcast is creating this problem so they can move you (charge) to their "unlimited data" plan. Which I finally succumbed to. Had outrageous data useage for a few months for no apparent reason - of course, if you pay for their X1 modem, they promise to be able to teack (I was using my own approved purchased modem). I purchased google wifi mesh router network in my home ot be able to track useage. One thing I would check - if you are using a device from your cell company (I had a Tmobile "Cell Spot") - apparently those devices act as a virtual cell tower for your cell phoine company and you cant restrict who can acceess data cell network through it - in other words, your neighbores could be watching movies using their own cell (non -wifi) and it may be going through your Wifi without your (or your neighbors knowedge) and using your data. The cell companies give these out free ususally to avoid having to build out their network where customers are experincing challenges. You cannot restrict who uses the "Cell Spot" its essentially a mini cell tower for anyone within range but goes over your internet data connection. Onme thing to watch out for. Ironically, asd soon as I subsribed to unlimited data, I've never had another month where data useage was high like before - how convenient Comcast. 

Yes, for the last 2 months.  The first month, xfinity waived the fee. The following month was an extra $60.  I still can't figure out why.  I've downloaded the app to see what device is using how much and when but it's not telling me comparison usage so I'm not sure what's more than before.

Have spoken to 3 people at Xfinity so far to no avail. My monthly data usage has been around 300GB per month since March 2020. January 2021 - 1400GB, February 2021 - 850GB so far. What is causing this jump? No one can find an explanation. We have watched the same amount of TV movies, used our devices about the same. No one else has been accessing our data. Can't figure out what changed in January and February. Any suggestions?

So, like many others in this thread, we've been averaging about 800G since pandemic started with two adults working from home and two kids required to be on zoom video class all day.

last night we get email notification at 12am saying we are at 75% usage.  Then at 3am, we get another message saying we are at 90%. Then another message at 6am that we are over 100%...  so how in the world does one use up over 300G overnight when everybody is asleep?  And now, as of noon were 100G already over the 1.2Tb cap.

how does one use up 400G in less than 12 hours!?

called Comcast and all they say is we used up one one courtesy over limit waiver, one day before the billing cycle ends.  and no explanation how one use up 300G in 6 hours and another 100G in 6 additional hours!  This is just ridiculous.  We don't have 4K (just plain ol 1080p).  Great way to treat a customer of over 15yrs.

AT&T just sent us mail we now can get fiber to the home.  We are definitely going to look into switching to them.

How do you monitor and throttle/alarm if you have excess network activity?

if it's caused by something like handshake error, how do you stop it before it gets out of hand? Most of our stuff is Mac or iOS.  Is there a software we can load on the laptop and iOS that will warn you if you go over some reasonable limit?

Welp.  That's roughly 29 Mbps if you pulled 300G in 6 hours.  Pretty much do able with 100Mbps service.  You can do it faster with better service.

I had an iPhone go insane while trying to download an update that failed from IOS 14.2 to 14.3.  That burned 90G speaking gibberish to Apple before I caught it, but my firewall emails me when excessive load is going on, and also daily status.  Software you install also likes to "phone home for updates", and that can hang too. 

Been there, done that with centrylink.  Wasn't a big fan of DSL speeds.  StarLink is $499 up front for hardware and $100/month.  Maybe that will come down at some point. 

I'm not using Xfinity gear, well...for a lot of reasons.  If you are, you are spending $14/month or $168/year.  In 5 years you will have spent $840.  You'll spend $30/month or $360 just the first year on unlimited.  What's an overage cost?  Maybe $200 max out of pocket cap?

You have budget to work with.

Buy a compatable gateway, run pfSense or opnSence (free) for a firewall on a dedicated x64 box or even an old laptop.  You can also buy a firewall appliance for less than $200 that will work fine.  Then buy a decent WiFi router and run all of your devices through the firewall.  Then you'll see everything.  The firewall is BSD based, so write any scipt you wish or use bsd tools like vnstat systat, even ifconfig  and toss it on a cron job if you want something else.  There are also addon graphing packages like ntopng and bandwidthd (free).

<- xfinity gateway ->< -firewall -><- internal wifi router -><- All Clients 

I also split the internal network too, for things I don't trust all that much, that don't have to talk to anything else like streaming devices/smart TV's.