No Cellular data after Wifi disconnection

There should be no “handoff”. LTE/5G should work whether you are connected to Wi-Fi or not. For example, I can be on a call with Wi-Fi calling, and if I move away from my Wi-Fi the call switches to cellular and continues without interruption. Unless your phone is broken, about the only things that can interfere with this is if you are using VPN (or even have it installed), or data corruption in your network stack. For the latter:

• Open Settings
  • Tap General
  • Tap Transfer or Reset Phone
  • Tap  Reset
  • Tap Reset Network Settings

• • This will erase all Wi-Fi passwords, but will not result in any other data loss.

There is no such thing as "Wi-Fi cellular”. Your phone can get an internet connection using Wi-Fi OR using Cellular data, never both. By default it will use Wi-Fi when you are near a Wi-Fi hotspot, and switch to cellular data when you are not within range of Wi-Fi. Wi-Fi range is about 150 feet, so unless you are home or in a location with a public Wi-Fi network your phone will use cellular data.

If your phone does not switch to cellular data:

• Go to Settings/Cellular and make sure it is turned on
• Also in Settings/Cellular make sure the switches for the apps you want to use are turned on
• Check for a carrier settings update by going to Settings/General/About and waiting for 30 seconds. If there is an update you will be prompted to install it
• If all of the above fails, contact your carrier’s tech support

If you are using VPN delete the VPN profile and app.

Does she also have 1-2 bars? They symptom you describe is what happens when the cellular signal is too weak to maintain a connection. It drops out, tries to reconnect, and if it fails it waits a period of time before trying again, the tries get further apart over time to save energy, and can get as long as 5 minutes. By putting it in airplane mode for 15 seconds or more that forces it to try again.

If this is the problem when you first disconnect from Wi-Fi it would say “no service”.

chemicalxv wrote:

I'm having the same issue, now on 17.3.1 with a 15PM. Don't know how long exactly it's been happening, but if this bug was "introduced" in 17.2.1 that might track.

Difference with mine is that my cellular data will start "working" about 20-30 seconds after disconnecting from Wifi, no phone restart, airplane mode on/off, or anything else needed. I've done a (physical) SIM swap and the issue still persists, so it's probably time to get a diagnostic done by Apple.

Go to Settings/Cellular:

Is Wi-Fi Calling enabled?

Is Wi-Fi Assist enabled?

Just adding to the, me too, in case this is a widespread problem. I have 15PM. At this point, I have to turn off wifi for it to connect to cellular. So even if I've left wifi, turned off wifi to force connection to cellular, use cellular connectivity and it works, if I turn back on wifi (even if I'm not connected to a wifi I know of), it will stop cellular. Weird.

vkseid wrote:

Just adding to the, me too, in case this is a widespread problem. I have 15PM. At this point, I have to turn off wifi for it to connect to cellular. So even if I've left wifi, turned off wifi to force connection to cellular, use cellular connectivity and it works, if I turn back on wifi (even if I'm not connected to a wifi I know of), it will stop cellular. Weird.

When you say it will “stop cellular” do you mean that you cannot make or receive phone calls?

When you have a Wi-Fi connection your phone stops using cellular data. It’s designed to do that. You should still be able to make and receive phone calls and SMS texts, receive Notifications, and update Visual Voicemail.

Further, if you have Wi-Fi calling enabled on your cellular account and it is turned on in Settings/Cellular then you don’t even need a voice connection to cellular.

I’ve had the same problem several times over the past couple of days. Each time I rebooted my phone and it took care of the problem.

Yes, I did, thank you but I’m not using a VPN. I’ve reset my network settings, wiped the iPhone, got a new SIM card, tried an eSIM… but I just realized it only happens when disconnecting from WiFi. If I stay disconnected from wifi cellular works but as soon as I reenable wifi, cellular data won’t connect. I’m going to try the beta iOS in hopes they have a fix.

I'm having the same issue, now on 17.3.1 with a 15PM. Don't know how long exactly it's been happening, but if this bug was "introduced" in 17.2.1 that might track.

Difference with mine is that my cellular data will start "working" about 20-30 seconds after disconnecting from Wifi, no phone restart, airplane mode on/off, or anything else needed. I've done a (physical) SIM swap and the issue still persists, so it's probably time to get a diagnostic done by Apple.

It has nothing to do with either of those settings. It doesn't matter if I leave the wifi coverage zone physically (ex. leaving my house) or manually severe the connection (ex. turning off wifi via the control centre), the result is the same - it takes a random amount of time for LTE/5G data to actually start working (despite my phone saying I have a LTE/5G connection). There's absolutely some kind of bug involved in the "handoff" if it's not actually a hardware issue.

This problem is also happening for me. Walking out of wifi from my house. Usually I will be watching a youtube video when getting the dog ready for a walk. I get about 100 feet from the house and it should connect to 5g or cellular. It doesn't. I have tried closing the app and reopening. Nothing. Other apps wont work that need to connect to the internet. Turning connections off and on don't work, (airplane mode, etc). I have to do a restart and it works just fine. But it happens every time. Looking for guidance. I tried all suggestions above.

I understand that. Wifi is my local internet from my home router. Cellular data is from the cell tower supplied by phone service.

I said “if I disconnect from wifi, cellular data no longer works.”

Again, if I completely turn off wifi and restart my phone, cell data works. Cell data stops once I turn wifi back on and then off - my phone no longer receives data from my cell service. I can reproduce it consistently.

Ive tried all your suggestions including talking with my service provider.

Thank you for the feedback.

Yes, exact same reception of 1-2 bars and when she disconnects from the wifi, the cell data works flawlessly. The main difference is she has a different phone.

And listen, I’m not blaming the software, just looking for a solution. It could be hardware, service, software, or a mix of them all.

[Edited by Moderator] 

My son is having the same issue as well. It just started a few weeks ago. His phone is used as a medical device and needs some sort of WiFi or cell to share data to the cloud and it can’t when it does this.

I’m also here looking for a solution.