VPN app won't work on cellular network

  • 14 May 2022
  • 5 replies


I have to log into an app for work through a VPN on my phone and I can’t get it to work on cellular data . I am using an iphone, it will work if I am connected to a wifi network but not on cellular data. I log onto the VPN app and shows connected, but then when I click on the app that I need to use it fails every time. Is there a way to fix this? Didn’t know if its a security thing with T-mobile  or not, it will work find and the Verizon or ATT networks on other phones I’ve tried.

5 replies

Hello @ibugu2,

It sounds like an IPv6 compatibility issue on your VPN (or possibly the company’s network). If the VPN or network are only passing IPv4 traffic, this presents a problem, since I believe that T-Mobile is IPv6.

This should not prevent you from connecting, but might require setting a second APN on your phone (I’d have to research how this is accomplished on iOS devices). Do you happen to know what VPN your company uses (e.g. MobileIron, WorkspaceONE, Intune, etc.)? 

If your company has an IT department (or IT person), that would be the first place to start. If not, I might be able to provide some more guidance on the steps necessary.

Userlevel 6
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It took some tweaking to get my phone’s Open VPN client to work with my VPN server. In the end it came down to setting the client to prefer IP over TCP transport. I’ve read various accounts of people getting their VPN clients working with company VPN servers and it sometimes takes cooperation of the company’s IT folks. For instance, they may have the minimum block length set too high.


It’s actually a program so I can control some car wash equipment for my business. The VPN app that the manufacture of the equipment uses is called ecatcher. It shows I’m connected to the VPN from ecatcher but then you have to go to the app Vijeo design to get into the controller for the equipment.


Userlevel 6
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What you want to do is try to see if you can “ping”* the internal side of the VPN router (e.g. If it answers your ping, then the problem isn’t with the VPN.


*PING is a networking test utility. You can get diagnostic apps that will run a ping.

@ibugu2, there is a discussion here about eCatcher and issues with IPv6 support on iOS version 15. It dates back to March, and notes that Ewon should have updated the application to address this. It’s not a definitive answer to your issue, but might point you in the right direction.

You might also want to look at what protocol that VPN client uses, and toggle to UDP if such settings exist. I do not have an iOS device handy to look (nor a networked control system!), but will keep looking.

Also, definitely good to test as suggested by drnewcomb. I have had success with the free version of Net Analyzer by techet. There’s also Fing and many others for ping and traceroute.