I have a Oneplus 7 Pro and the app is not working. Everything else works fine. I’ve reinstalled the app multiple times. Here is a video of what it’s doing.
Hello Ulludan 
Sorry to hear you’re having issues connecting with the Companion app… do you have any other Blizzard apps on the phone, like Hearthstone? If so, do you have issues connecting with that?
Are you able to change your network type? i.e. if you’re on a home wi-fi, change to mobile data, or vice versa, and see if the issue persists.
If mobile works, but then switching back to wi-fi doesn’t, then you’d want to troubleshoot your home network devices:
Power Cycling Your Network Devices
Best of luck in your adventures 
I can log into hearthstone just fine. The companion app will only work while I’m connected to WiFi apparently. Restarting my phone doesn’t change anything. Every other app works perfectly on WiFi and data.
Hey there Ulludan,
If the problem is only happening on the cellular data network, it might be best to contact the network provider directly for assistance. They can help verify if the data plan is “capped” or similar, which can cause issues like these.
It’s not. Everything else works fine. The one and only thing not connecting is your companion app.
For argument’s sake, do you know anybody else who plays? Can they connect to the app via your phone?
Apart from that, I’d reinstall the application, and power off your phone for 10 minutes then turn it back on. The last thing to try would be clearing the app cache. How to do this last one varies per phone - you’d want to look up how to do this online for your Operating System/Phone.
As shown in the video it doesn’t get to the log in screen at all so no one can log in. According to Oneplus and TMobile, because every other app works just fine it must be on blizzards side. All of your suggestions have already been tried multiple times.
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Ulludan,
It’s definitely possible, though I have my doubts due to the fact that the application works fine on your wifi and not your data. The question I was asking earlier was diagnostic to try and find the problem. If you do know anybody else, or have a second account, can you have them log into the app while connected to wifi, then swap to 4g and see if that helps? We had a few people test in our building on 4g and ours appear to work.
I have the exact same issue since the update for the last patch. It works over WiFi but not data, all other apps work over data. Because of the timing with the app update, I’m inclined to blame the app, but in the interest of full disclosure, I am also on T-Mobile.
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Grealt,
I can see if we have someone on that service who can reproduce the problem, but can’t guarantee we’ll be able to do so. That said, it seems to work in all cases we’ve tested so far. Based on the fact that you’re both on the same cell carrier, it’s possible there’s an issue with whatever network they use to deliver your connection from your phone to our servers. Even if it’s not your local cell tower there’s a possibility somewhere between you and us there’s some kind of overload.
For the time being your best bet is going to be reporting the problem to T-Mobile and letting them know that it seems to work for most players on 4g, but for some reason it’s not working for you. You can use your wifi to connect to the app for the time being, though I know it takes some of the usability ‘on the go’ out of the app.
Same here. Tmobile network. Companion app works on wifi, but on mobile network no luck.
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I am having the same problem, I can connect to the app on WI-FI but not on data. I have Metro PCS (on T-Mobile network). Like another user pointed out, this issue started with the latest patch.
HOWEVER, my wife is on my Metro PCS plan and she has absolutely no problems logging into the app on either WI-FI or data on her phone. She has an older Samsung J7, I have a Samsung S9.
Same problem with me. Ever since a update months ago i can only use the app while connected to a wifi.
Samsung Note 9
Unlimited data
T-Mobile
Same issue here works on wifi but not tmobile data
Hey all,
So far it’s sounding like all the reports are happening only on connections through T-Mobile. The best thing to do would be to contact them directly to report the issue. Let them know that the problem only happens on their networks (since it works on wifi).
Already did nothing on there side they can see or do
But it worked fine before this last update, wouldn’t that be something for Blizzard to look into? Worked on same phone, same network, until new update (makes it an issue for Tmobile)
I’m a little confused … 
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It’s Blizzard responsibility to test their app on all networks. Your QA team should have captured this issue while testing new version before it was released. Blizzard please have your developers fix this issue.
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I am having this issue with Google Fi (using the t-mobile towers), when i change to the Verizon towers, it works fine…same phone, same app
Out of curiosity, has anyone tried a VPN while on the T-mobile towers? Support cannot suggest any specific program or provide setup instructions for third party software, but it may be a way to test the problem.
Update:
We are investigating this internally. However please do still contact T-Mobile to ensure they are informed and aware of the issue.
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