But do I also disable it for the wwan0 card as well?
Alright I disabled ipv6 globally on the phone and weāll see if that was the culprit. While I logically know that we have to migrate to IPv6 I canāt stand it at the same timeā¦lol.
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I have experienced the phone using the mobile data instead of wifi when I get IPv6 from both wlan0 and wwan0.
My plan has unlimited data so itās not something I track closely, but it does impact performance of certain tasks. For my use case I can just turn off mobile data during that task, but once turned back on it does sometimes revert back to preferring the slower mobile data connection which is especially annoying when the modem ends up in a state where the mobile connection is no longer working properly so data stops working even though Iāve got a perfectly good wifi connection as evidence by how well it works when I kill the modem to reset it and get the modem back to a functional state.
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Note that you can have the opposite problem (as I do) i.e. home WiFi gives fully working IPv6 goodness but mobile service providers here generally donāt have IPv6 at all.
Almost 25 years down the track, unfortunately IPv6 deployment is still spotty and incomplete, leading to annoying failure cases, as being discussed here. (Other e.g. canāt use Office365 from Thunderbird unless you disable IPv6 in Tābird 
)
Ok this is getting ridiculous. Itās April 10th and Iāve used almost 3 gigs of my 5 gig plan and Iām exclusively using wifi for everything as I have a hotspot on my other phone. I have disabled IPv6 globally on the phone. This is unsustainable, I wonāt be able to afford to use this phone if it continues to burn through data with reckless abandon.
Is anyone else experiencing this phenomena?
Iām not. Iām getting an SMS from my provider whenever I reach 300MB of transfer in a single day and it only ever happens when WiFi is turned off.
Has never happened to me, either.
Iāve tried using nethogs to find the culprit but it doesnāt seem to point out any issue. Iām wondering if I need to reflash my phone?
Are there any other tools I can use to sniff out what is consuming traffic on the wwan0 card?
Wireshark?
tcpdump -n -i wwan0
and watch its output esp. when you donāt expect any
There are a few scenarios where data will continue to use a particular network even when another network/interface/route with a higher priority becomes available.
I get round the problem by hooking into NetworkManagerās dispatcher system to conditionally block/unblock mobile data when wifi/ethernet network/interfaces come up/down.
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I have found as well that nethogs shows traffic not associated with a device at least not one it is showing me. Under program it shows āUnknown TCPāā¦also seeing 0.0.0.0:4954-0.16.0.0:44099 in nethogs which is not being associated with a device either. I might investigate if either port 4954 or 44099 is associated with any service. Seems very odd to me.
This command tells mw that wwan0 does not exist which makes no sense. So I just have it generically listening to all traffic and lo and behold itās showing IPv6 traffic again which I thought I disabeld globally. I used:
sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=1
And that has obviously not disabled ipv6. Is there some way to turn it off permanently? I understand that IPv6 can cause this kind of behaviour. I know on our mobile network IPv6 isnāt officially out yet but it is running as I know I was getting an address on both the wlan0 and wwan0 adapters.
So I disabled IPv6 permanently by adding a line to the sysctl.conf file and now monitoring both the wwan0 and wlan0 with tcpdump and so far so good. I guess I assumed the previous commands made permanent changes but that isnāt the case it seems.
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Iām also experiencing the same issue, turned on IP6 on my router and made changes suggested by others on the forum but still uses up my monthly allotment plus the extra I purchased. I turned off the mobile data on the phone.
Using tcpdump I believe like someone else in here suggested that the phone is quite sloppy with handoffs when switching to and from mobile data to wifi. It seems that when you go from mobile data to wifi, the mobile data connection lingers even though there is an unmetered network available. Some have suggested that itās the particular app that is the issue but I think the OS needs to enforce the metering or we will be faced with this issue forever if relying on app devs to honour the metered networks.
I think in the meantime we need to be vigilant about toggling the wifi on and off as you transition between wifi areas. I think this really needs to be looked at and made a fairly high priority. Not all of us have unlimited data plans.
I think if the network is āmeteredā then it essentially just means the system wonāt automatically install updates. I donāt think that it enforces that on apps the way android does.
If that is the case then there needs to be the ability to control bandwidth usage in a granular fashion or else this thing will be a real burden and also a pain in the rear to be constantly monitoring the network usage. It will be like EVās with range anxiety, except it will be data anxiety instead. Obviously Iām not alone in this as others have the same concerns.
I understand that mobile linux is really very much a dev project and not nearly close to being out of beta I would say, I get that, but I think this issue should not be ignored just because some people have unlimited data plans and donāt really care about it.
Its tricky because I believe the root underlying issue is how to get Linux to hand off a connection from one interface to another (eg, wwan to wlan) without losing the connection. I think android and iOS can pull it off because of unique device identifiers, but obviously pureos doesnāt have that, and therefore the cell modem hangs onto the connection at least whenever its actively being used instead of just handing it over to wifi.
So all that to say that, in my opinion, the real problem is how do you describe to the OS when itās OK to drop a cellular data connection and when itās OK to make another one?
Edit: Iām sure the modems being separated from the CPU doesnāt help anything either.
But isnāt the fact that the cell modem is called wwan0 and the wifi card called wlan0 unique identifiers? Unless Iām misunderstanding what youāre saying. Couldnāt there be some sort of user assignable watchdog that the user can decide, when network A is available use that network and only use B if A isnāt available? I thought thatās what the priority setting in Advanced networking does but that doesnāt seem to work at all or at least not that I know of.
This isnāt really a new concept as in routed networks itās called least cost routing where you can assign a cost to a particular interface so that it only uses the higher cost interface if the primary one is full or not available. So Iām not clear then on what the purpose is of setting the priority in Advanced Networking is for if that is not what itās doing.