Solved 3CX IOS app will not allow connections via WiFi - 3G/4G no problem

[Shobosh]

Dear all,

Strange one this.

We have a customer with the latest iPhone 12 handsets running IOS 14.

Using hosted 3CX (Version 18), the handsets can connect to the PBX fine using 3G/4G.

However, none can connect using WiFi. We have tried different routers - even different sites. The 3CX app reports "Connecting........" <forever>

Is this a known issue with hosted 3CX Version 18 and IOs 14?

Much obliged,

Shobosh

 

[Vali_3CX]

@Shobosh
Can you open from iPhone's Safari the 3CX Management console when on WiFi?
Also, it's that WiFi a restricted one? I mean, which blocks traffic on all ports except 80 and 443.

 

[Alphabetic]

What DNS server does your wifi give out?

I would download a ping app and ping your FQDN on the wifi to see if it's resolving.

 

[MartijnDoeland]

I have the same problem,
Try this (works for me): in the wifi-settings on your iPhone: Disable the 'use private address'

https://support.apple.com/en-us/HT211227

 

[Shobosh]

Hi kieferschild,

I have found I have a DNS resolution issue, as suggested above. However, I'm not sure how to resolve it. Intriguingly, laptops and PCs connected to the same wireless router works fine.

I'm not sure how to resolve this issue on the iPhone.

Any thoughts or suggestions?

Regards,

Shobosh

 

[ChrisC_3CX]

@Shobosh

To confirm it, an idea would be to try manually setting google's DNS servers (8.8.8.8 and 8.8.4.4) on an affected iPhone, disable enable Wi-Fi and try again.

 

[Shobosh]

Thanks Chris,

I confirm I am no further forward. I applied the "Manual" DNS settings.

I get "Cannot resolve host" if I attempt to ping the FQDN (customerinstance.3cx.co.uk). It's not a router issue as other devices on the same network are connecting OK. It's something specific to the iPhone !?

Well weird !?

Rgds,

Shobosh

 

[Alphabetic]

What wifi solution are you using?

Are you able to ping the FQDN via a laptop connected on the wifi?

"s other devices on the same network are connecting OK." - Please clarify what devices and what you mean by connecting ok

 

[Shobosh]

Thanks Chris,

I confirm I am no further forward. I applied the "Manual" DNS settings.

I get "Cannot resolve host" if I attempt to ping the FQDN (customerinstance.3cx.co.uk). It's not a router issue as other devices on the same network are connecting OK. It's something specific to the iPhone !?

Well weird !?

Rgds,

Shobosh

I confirm I can access customerinstance.3cx.co.uk Management Console via Safari

 

[Shobosh]

I can fire up the Web Client on PCs and laptops on the same network, via WiFi (same SSID).

I can resolve customerinstance.3cx.co.uk to an IP address from laptops and PCs on the same network.

 

[Shobosh]

Might this be a contributing problem with 3CX app on iPhone.

https://www.binwang.me/2020-11-08-DNS-Resolving-Bug-in-iOS-14.html

...or is this a distraction?

 

[Shobosh]

Another observation that's a bit strange.

With the latest 3CX app installed and the iPhone connected to the internet by WiFi, the 3CX app reports "Connecting ........"

However, the handset rings on incoming calls, which you can't answer!?

 

[ChrisC_3CX]

@Shobosh

The fact that this is a 3CX Hosted instance and the 3CX iOS Windows app works when on an LTE connection, suggests that the issue most probably has something to do with the wifi network the iOS is currently connected to.

That said, before spending time investigating I suggest first confirming this by simply trying on another wifi network which you know works, and then review the configuration of the affected network in order to determine what might be causing the issue.

The fact that you receive the call but can't answer indicates that communication between the iPhone and Apple's servers is Ok but you might have issues contacting the 3CX PBX. If you see presence information such as, other extension status, etc that means that contacting the 3CX PBX on HTTPS port 443 must also be okay which means you might have to specifically look into the traffic used by the 3CX's Tunnel which would be traffic to and from 3CX's TCP and UDP port 5090.

 

[MartijnDoeland]

Switch off the private address in your wifi settings on the iPhone.

 

[Shobosh]

Switch off the private address in your wifi settings on the iPhone.

Thanks @MartijnDoeland

I see that works for some people, but not for me. The issue remains.

 

[Shobosh]

@Shobosh

The fact that this is a 3CX Hosted instance and the 3CX iOS Windows app works when on an LTE connection, suggests that the issue most probably has something to do with the wifi network the iOS is currently connected to.

That said, before spending time investigating I suggest first confirming this by simply trying on another wifi network which you know works, and then review the configuration of the affected network in order to determine what might be causing the issue.

The fact that you receive the call but can't answer indicates that communication between the iPhone and Apple's servers is Ok but you might have issues contacting the 3CX PBX. If you see presence information such as, other extension status, etc that means that contacting the 3CX PBX on HTTPS port 443 must also be okay which means you might have to specifically look into the traffic used by the 3CX's Tunnel which would be traffic to and from 3CX's TCP and UDP port 5090.

Thanks @ChrisC_3CX

I confirm the issue is consistent - no matter which SSID the customer uses. On returning home, we tried the connection using his home "BT Home Hub" (installed 2 months ago) and we have the same issue. Switch over to 3G/4G and the 3CX app immediately connects.

When connected to WiFi, the 3CX app reports "Connecting........"

Presence info cannot be seen on the iPhone when this happens (connected to WiFi), yet other devices on the network using the 3CX Web Client work perfectly.

I have tried creating a new extension, making sure the STUN settings are set correctly on the Management Console, send out a welcome email, scan in the new definitions and the issue prevails.

In passing, my Android handset works perfectly when provisioned on my customers extension (!). I deduce the issue must be something to do with iPhone IOS 14

I confirm changing the state of the "Private Address" switch in the IOS WiFi settings has no effect.

I really am stumped with this one.

 

[ChrisC_3CX]

@Shobosh

I'll send you a PM shortly so that we can gather more information regarding this issue.

 

[Shobosh]

Thanks for you help and PM @ChrisC_3CX

I think we might need to park this one for a day or two. I have asked the customer to switch WiFi off in the short term until I can get back on site. He can work fine on 3G/4G.

I will escalate/progress the matter in accordance with your PM instruction and come back to you soonest.

Much obliged

@Shobosh

 

[ChrisC_3CX]

@Shobosh

Understood! Let us know once you're able to do so.

 

[Shobosh]

Dear all,

Thank you for your valuable help and suggestions. I managed to find an identical test iPhone running the same version of IOS (14.6) as the problem handset.

Having set up the test handset with the 3CX IOS app and scanned the QR code, it worked first time - both on WiFi and 3G/4G.

I deduced the issue was related specifically to the problem handset and not a config or network issue. I followed the forced reboot procedure to clear all cache and the procedure resolved the 3CX app problem. Evidently, the cache needed to be cleared.

I took far too long to resolve this issue! Thanks again for all contributions.

Best regards,

Shobosh