How to find the bandwidth usage by each device on my network?
December 1, 2019 11:59 AM   Subscribe

In the last 4 months, our data usage has doubled from 450Gb in August, to 1Tb in October and November, one time exceeded the 1Tb data cap that Comcast has. How can I find out what device is causing the increase? To my knowledge, there's been no change in our data usage habits.

We have a Motorola cable modem that connects to a T-Mobile supplied Asus TM-AC1900 WiFi router. There are five devices connected directly by ethernet cable (including an ethernet switch), and a number of phones, tablets, laptops (Windows) and one iMac that connect via WiFi.

The router doesn't have a means of displaying data usage by device (other similar ASUS routers can do it, but the TM-AC1900 hasn't had a firmware upgrade for some time, and it's impossible to install an open source firmware upgrade that can show data usage per device.)

Has anyone used and can recommend a network monitoring tool that can do this easily (and preferably for free)? I have found software like Glasswire that can monitor a single computer's data usage, but I want to know the data usage of every device on the network.
posted by ShooBoo to Computers & Internet (11 answers total) 4 users marked this as a favorite
Have you tried downloading the xFi app? I can see which devices are connected, how much they are using, etc. I am not sure if this is only possible because we have some Comcast pods but it’s worth a try.
posted by JenMarie at 12:15 PM on December 1, 2019

Unfortunately, as I don't have an Xfinity gateway, I can't use the xFi app.
posted by ShooBoo at 12:24 PM on December 1, 2019

Oh got it. Comprehension fail on my part. Hope someone else has an actual helpful answer!
posted by JenMarie at 12:28 PM on December 1, 2019

You have to have the traffic on the network go through a device to capture which machine is doing what. Many routers support this as a feature now, but its a pretty recent addition.

This device could be the router or a transparent proxy. If you had an extra computer to install Linux on and had sysadmin skills you could do this. Some parental control system also do this (like MyCircle)

If you do not have those skills and cannot afford replacing the router with one with a per device monitoring feature I would see if you can check the bandwidth usage over time of the network. Then you can do ahead and turn on or off certain devices and try to figure it out that way.

If it is one device using a lot because of some weird issue (malware or new software) you should be able to figure it out this way.

Lastly there are Ethernet sniffers (like Software that can watch traffic. This is likely to be harder to sort out because the hard wired devices all go through Ethernet switches. So you cannot see all the traffic from a single computer on the network.
posted by creiszhanson at 3:43 PM on December 1, 2019 [1 favorite]

Do you have both MAC filtering and a strong password (like one generated by a password generator)? Someone could be leeching from your wifi...
posted by lalochezia at 5:10 PM on December 1, 2019 [1 favorite]

The same evening I read this question I also read this article about residential internet customers possibly fronting a lot of traffic unbeknownst to the customer, including Comcast and other providers.

I realize the actual question is how to find out which device is doing it, but I thought the article might be of interest to the OP as a possible explanation of why it may have started (?).

The mods can certainly delete this answer if I have stretched the limits.
posted by forthright at 6:09 PM on December 1, 2019 [1 favorite]

You have to have the traffic on the network go through a device to capture which machine is doing what.

I don't think 'through' is really the case. On a particular subnet, all the traffic goes to all the clients, and they each ignore the stuff that's not addressed to them. That's how things like WireShark can work. I think you can make WireShark log traffic loads, though it's not something I've tried.
posted by pompomtom at 6:26 PM on December 1, 2019

PomPomTom, that is incorrect. A switch will use forwarding tables to send out traffic to relevant ports only. In the early 90s we had hubs that would broadcast traffic to all ports, but switches are more advanced.
posted by nostrada at 7:07 PM on December 1, 2019 [1 favorite]

Thanks for the correction.
posted by pompomtom at 11:52 PM on December 1, 2019

Is anyone in your household running Bittorrent? I only bring this up because 1TB is a ton of bandwidth to go through in a month. That's over 30GB a day.

I'm a pretty heavy bandwidth user (uncapped fiber at home) and torrent uploads are a major portion of my use. Especially public torrents, if you're seeding those at high speed then you'll get a ton of activity on them.

So I'd see if maybe someone downloaded The Mandalorian or something and forgot to close qBittorrent or pause the torrents afterwards.
posted by neckro23 at 8:46 AM on December 2, 2019 [1 favorite]

Not really a direct answer to your question, but that type of jump could be typical if you do a lot of streaming and made any changes to your hardware or software that included a bump in resolution. If you used to stream in 720 or 1080 and suddenly jumped to streaming in 4K, or started using a fire stick instead of your smart TV app, doubling the data volume would not be unusual.
posted by Short End Of A Wishbone at 11:15 AM on December 2, 2019 [1 favorite]

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