Unusually high data usage megathread

is it possible for a NON 4k tv to use 980 something gigs of data in a 24hr period?
this seems extremely high to me and extremely unlikely 

Why would my WiFi usage go from an average of 150 GB to all of the sudden over 1 TB. I've added an x-box but it replaced a PS4. I have added a WiFi extender, could it be using that much data? I have looked and don't see anything not recognized as one of our devices. Thanks for any help.

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@RobertWy wrote: 

Data usage is not dependent on a TV; it is the amount of data used with the Internet connection.

I watched JacK Ryan last month with Amazon Prine and almost went over the 1TB cap.

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Perhaps you were close to the cap to begin with ?

I think it is very unlikely that a TV would use 980GB in a day and I would be looking for other causes.  People tend to focus on things they do directly like watching TV, but that much data that fast is more likely due to a backup program, software updates etc. that may be happening automatically.  Also keep in mind that data on the meter may be delayed up to 24 hours, so something that appeared to happen on a given day may have really happened the day before.

@sal826

I ran into a similar problem myself.  Wireshark on your LAN is fine for outbound analysis, or inbound if you're intentionally running some kind of "service",  but what you can't see is what is hitting your WAN IP from the cable modem perspective.  Modem might have a firewall that could be partially blinding you.  First, is it enabled, and then, is it responding correctly?  It's a more complex question.  Assuming your cable modem doesn't have a known exploit:

Consider a SYN attack.  If you have ANY port that will respond on your cable modem, a "not very nice" external user can send you a synchronize packet, your open port will respond with SYN-ACK.  Depending on the attack method, that packet from your modem will either go to a bogus IP, or they can discard it quietly on their end with a firewall rule.   In any case, the 3rd part of the handshake, the client ACK your modem expects -- never happens and times out, so your port is left in a half open state.  The object is to either cause a DoS, or exhaust your resources and force a buffer overflow.  Optionally, use the half open port for some other kind of exploit attempt or more complex intrusion attempt.

You'll find this to be a fairly effective method to generate a huge amount of data with limited external resources, and this is only one example.

First thing I'd do us use a utility like nmap from an external location and see if there is ANY response from ANY port on your external cable modem IP address and go from there.  Nmap should tell you "filtered", and not open or closed.  Filtered means zero response.  If you are actually running a service of some kind on your LAN and port forwarding, or using/allowing UPnP from internal devices, I'd be looking at that pretty carefully.  Hide in plain sight too?  Yeah, well....disabling ICMP is always a good idea and that is always another traffic source.  Script kids usually don't use the -Pn option in nmap for portscans so no ping response generally means a pass over, but not all the time.

In my case, I was able to cut traffic by more than half with draconian adaptive firewall rules and routing through a seperate firewall box before the cable modem.  Cable modems are not reliable firewalls.  If you do find a port that doesn't behave or a service you can't disable, sometimes you can forward the port off into the bit bucket (bogus IP), or let it hit an internal firewall directly with a port forward to a firewalled port (preferred).

Now I have another situation where the usage Xfinity reports, is actually LESS than what I honestly know I'm using.  Now where that delta comes from is really unknown.  Averaging error on their end?  Timing thing? Retransmit banking off something.....but only sometimes?  Unknown.  I can see every packet that goes out, or comes into the WAN interface.  I'm still trying to figure that out.  Maybe it's just a firewall artifact on my side..........

Well, I'm 7 days into the month and I'm at 273gb.  That's averaging a reported 39GB a day based on the uasge outside the 24 hour delay.  39GB A DAY!!! Really.  In tired of seeing the same ole same ole default responses here by Comcasted of minimize this and minimize that, which minimizing the redundant repsonses would be good, lets do some math; averaging quality between 1080 and 4k, lets use 2K streaming roughly 3GB per movie.  So at 39GB/3gb per movie, that puts me roughly at  10 movies a day, give or take.  So even if the movie lenght averaged out to 2 hours per movie, that would be 20 hours a day watching movie.  Where does that make sense for someone working 8-10 hours a day with 1 kid in school and the other one napping half the day.  This data usage makes no sense at all given the data usage habits haven't changed since thee months of Sept, Oct, and Nov where I used roughly 500-600 GBs, A MONTH!  Then all of a sudden Dec and Jan are showing that I'm using double to triple that?  Nothing on my end has changed.  I reset my network ssid and password, I even swapped out the modem at the request of tech support, yet I get the same BS response that nothing can be done and that I'm using that data somewhere.  If this continues to show this kind of usage, I'll be forced to cancel my services and move over to the competitor.  I won't pay overages and I'm not switching to unlimited! The fact that comcast does nothing about all these people complaining about the same issue is just ludicrous.  At what point does comcast research the issue in their systems and stop looking at the user's modem reports or account usage reports?  There are signs of something more here that comcast is missing.  You've had previous instances of software updates on your end causing a miscalculation on your network.  Could it be a simliar issue?  Was there a software update at comcast recently that cause a glitch in your systems, AGAIN?  Why are so many people having the same issue?  This is not a sparse issue.  You should probably look into it further instead of continually suggesting people check their networks and usages and minimize this and that.  I didn't get internet to minimize my usage on it if I didn't change my usage habits.  Figure this out or you are going to lose more customers!

Have they switched back to the new metering system that was shown to overbill customers?   I have noticed my usage is higher this month than the previous 4.  The only thing going on this month is Netflix streaming.   Maybe 2-6 hours per day due to multiple devices.  Yesterday  no one streamed anything and I still used 27 Gigs of data from the prior day.   I have Netflix set not to stream in HD.  How much data should Netflix use per hour?    According to Xfinity that should be 2-6 gigs per day.  

Between this constant need to monitor and try to figure out what is going on with my data, not having ACC Network AND a price increase, I am about ready to pay the penalty and switch back to my previous provider.  

even now the January billing, From Jan 1- Jan 7th my google wifi app shows i used 65.8 GB and my xfinity account shows 132GB data used. Something is really off.

Why can we not see the data used when using apps through our xfinity box?   Also,  why can we not see how many gigs each device uses?  They show a percentage, why not the actual usage from that device?  Then we would know how much data a particular show/app is using.  

*** I HOPE THIS HELPS OTHERS ***

In October 2019, I received a notification from Comcast (Bay Area) to upgrade to a new cable modem that supports DOCSIS 3.1 to take advantage of higher Internet speeds. I upgraded to the MOTOROLA MB8600 in mid-November 2019.  In December 2019, I randomly (no notification from Comcast) saw my Monthly Data Usage exploded past 1 TB - we're consistently under <=200 GB/month.  Our Internet usage pattern did not change nor did we add any new devices and/or services. Without an explanation from Comcast, I reverted back to my old cable modem. Since then we have seen our Monthly Data Usage back to normal. I've concluded this to be a bug with Comcast and/or the cable modem software.

Here's an article on this, but doesn't look to be resolved: https://arstechnica.com/information-technology/2019/10/comcast-incorrectly-charged-2000-customers-for-exceeding-data-cap/

Apparrently I'm not the only victim. . .  Two retired people here who consistently used less than 100 Gb/month with ATT. Now after switching to Xfinity for faster internet, all of a sudden we used 1052 Gb our first full month with no change to our usage habits. Ridiculous! 

Looking for a robust write up of what counts against the Data Usage. I listed out some examples that would give you a idea of the information I am looking for.

Xfinity mobile phone using wifi calling on home wifi
Xfinity mobile phone using data on home wifi
Xfinity mobile phone using data on public home wifi
Xfinity X1 streaming Amazon Prime show through Xfinity application on home wifi
Roku BritBox streaming on home wifi

This is not complete, but tends to cover general areas. Apoligize if this has been asked and answered already.

Hello, 

I need a way to get actual data usage by device (not just a percentage.) Any help is appreciated. thanks!