Error on iPhone - "A TLS error caused the secure connection to fail"

[CountMagnus]

Was just setting up an iPhone to work as a new extension and scanned the QR code and got this error. "A TLS error caused the secure connection to fail". Does anyone know what it means ?

 

[KyriacosS_3CX]

Hi,Other devices work OK, PBX login via browser is fine? Can you remove and re-add the app on the phone?

 

[ThomB_3CX]

Can you also try logging in to PBX via your iPhone's browser?

Thanks

 

[CountMagnus]

Thanks for your help with this. As you explained all other functions are working fine. I have removed the Phone but it will not add back for the same reason. Other phones now appear to be effected in the same way but some of them are OK.

 

[CountMagnus]

Will Try to log in via the Phone Browser

 

[CountMagnus]

Sorry for the delay. Have just checked and I can log as the Admin from the iPhone's browser. All worked OK

 

[CountMagnus]

Any ideas why I can not set up the iPhone to work as a new extension when I scanned the QR code. Still get the error. "A TLS error caused the secure connection to fail". Does anyone know what it means ?

 

[paulodagraca]

Hello CountMagnus,

Could be the smartphone:
Did you try another phone?

Could be network connection / blacklist:
Another WIFI of 4G/5G connection on the smartphone? (other location)

Could be the APP installation:
Remove / re-install the 3CX APP

Could be the QR code:
Create new user, scan this QR directly from Admin - Users panel

If all this is good, it should work.

Paulo

 

[CountMagnus]

Thanks for the help. I had the problem on an iPhone that had worked for some time (Years). My iPad is still working fine. I have uninstalled the App and reinstalled and I have also set up a new extension and I still get the same error when I configure the iPhone using the QR code. I have tried on the same wifi network as the PBX Server and on 4G. Still have the same problem. Any further ideas ?

 

[paulodagraca]

Hello @CountMagnus ,

Basically it is your iPhone that has a problem.
I don't have an iPhone, so i did ask ChatGPT to help, and this is the answer:


The “A TLS error caused the secure connection to fail” message on an iPhone usually means something is blocking or breaking the encrypted (HTTPS) connection between Safari (or an app) and the website.
Here are the most common causes and fixes you can try, in order:

---
Quick Checks

1. Reload the page – Sometimes it’s just a temporary network glitch.

2. Try another browser/app – Open the same site in Safari, Chrome, or another app to see if it’s app-specific.

3. Check another network – Switch from Wi-Fi to cellular or vice versa.

If it works on one but not the other, the issue may be your Wi-Fi/router.

---
Fix Date & Time

TLS requires your iPhone’s clock to be correct.

Go to Settings → General → Date & Time

Turn on Set Automatically.

---
Reset Network-Related Settings

Forget & reconnect Wi-Fi

Settings → Wi-Fi → (i) → Forget This Network → reconnect.


Reset Network Settings (won’t delete data, but will remove saved Wi-Fi passwords):

Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings.

---
Update iOS

Older iOS versions may not support the latest TLS standards.

Settings → General → Software Update → Install the latest update.

---
Check Content Blockers / VPN / Proxy

Disable VPN (Settings → VPN).

Turn off Private Relay (Settings → [Your Name] → iCloud → Private Relay).

Disable ad blockers or security apps that might intercept traffic.

---
Check Certificates (if it’s one specific site)

If the problem is only with one website:

The site’s SSL/TLS certificate may be expired or misconfigured.

You can verify by opening the same site on another device/network.

If it fails everywhere, only the site owner can fix it.

---
Last Resort

If nothing works:

Restart your iPhone (simple but effective).

Try accessing the site from a different device to confirm if it’s a server-side issue.

---
Summary of Most Effective Fixes:
- Set Date & Time to Automatic
- Reset Network Settings
- Update iOS
- Disable VPN/Private Relay

Paulo

 

[CountMagnus]

Hi, This sort of helped. I checked the HTTPS address that I was using to log in and it was not using the 3CX FQDN. Therefore I changed it to the 3CX FQDN address and this address would not connect to the server. I deactivated the Pi Hole and tried again and it worked. I then activated the Pi-Hole and it has remained working for a while and then stopped and then started again and has been fine for a while with the Pi Hole activated. So not sure if the Pi Hole was the problem.

I then tried the 3CX FQDN address from my phones browser and it would not work. Then I tried again and it did. I then tried the APP on a new extension. This worked but the extension shows as not registered. I can make calls from the 3CX App but can not receive them.

Does this help with giving you any ideas on what the problem is ?

 

[SteveITS]

extension shows as not registered. I can make calls from the 3CX App but can not receive them.

Enable browser notifications…bell icon upper left.

 

[CountMagnus]

Steve. Thanks for the help but I can not find the bell icon within the iOS app on my iPhone. Where is the setting?

When logged into the browser on windows 10 it works fine. I can also make and receive calls within the browser when logged into the url on the server. It’s just the iOS app that does not work.

 

[SteveITS]

I misunderstood, I thought you meant the web client. The mobile apps don’t have that. You mention connectivity issues above so probably that?

 

[CountMagnus]

I have had a look at the config for my Pi-Hole and I realised that within its Local DNS list I had both of the following.

xxxxxx.my3cx.co.uk --> IP address of the 3CX server​

my3cx.co.uk --> IP address of the 3CX server​

I have now deleted

my3cx.co.uk --> IP address of the 3CX server​

and it appears to now be working fine.

The strange thing is that it has been working fine with this config for years and its only since around the time of IOS upgrading to 26.0.0 that the issues started.