T53 can't connect from one location

[SteveITS]

The server is hosted externally to the client's office.

From their office this phone connects fine, and is set up as a router phone, and it shows in 3CX as connecting through itself.

If that person brings the phone home, that phone:

• does not connect to 3CX
• shows No Service
• cannot connect to NTP ("Fail to sync NTP time(pool.ntp.org).", and cn.pool.ntp.org)
• thus the date/time is the Yealink default for the installed firmware
• can resolve hostnames via DNS
• can ping (e.g. ping google.com or 8.8.8.8 from the phone diagnostic page)

If he brings the phone back to the office, it connects to 3CX just fine.

He reports his ISP, Comcast, says they aren't blocking anything. Obviously this seems incorrect. Any suggestions as to what to look for or ask Comcast?

I have tried firmware .77, .76 (original), and .74, currently on .77. I have tried setting the time on it, to no avail.

His home IP is not blacklisted on the server or by our data center router, and he can connect to the web client from a PC at his home.

Log excerpt:
Aug 17 00:02:10 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:02:14 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
Aug 17 00:02:17 ATP [1563.1578]: DURL<3+error > [DCMN]download common error, errcode:28, no out.
Aug 17 00:02:21 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:02:25 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
Aug 17 00:02:32 sys [1318.1324]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:02:36 sys [1318.1324]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
Aug 17 00:02:38 ATP [1563.1578]: DURL<3+error > [DCMN]download common error, errcode:28, no out.
Aug 17 00:02:39 ATP [1563.1578]: ATP <3+error > Get redirect error.
Aug 17 00:02:39 ATP [1563.1578]: ATP <3+error > get RPS url error.
Aug 17 00:02:39 GUI [1410:1410]: APP <3+error > 559.753.828:from[app_vpPhone] sync[0] msg[395223][0][0] size[0] target[0xc4a5bd38] not found
Aug 17 00:02:42 GUI [1410:1410]: APP <3+error > 562.752.679:from[app_vpPhone] sync[0] msg[395223][0][0] size[0] target[0xc4a5bd38] not found
Aug 17 00:02:43 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:02:47 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
(...NTP log entries repeat...)
Aug 17 00:04:00 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:04:04 sys [1318.1323]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
Aug 17 00:04:07 kern[0.0]: KMSG<3+error > mk:no target(0xc4a5e074) call msg from autoServer
Aug 17 00:04:11 sys [1318.1324]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).
Aug 17 00:04:12 kern[0.0]: KMSG<3+error > mk:no target(0xc4a5e074) call msg from autoServer
Aug 17 00:04:12 kern[0.0]: KMSG<3+error > mk:no target(0xc4a5e074) call msg from autoServer
Aug 17 00:04:12 kern[0.0]: KMSG<3+error > mk:no target(0xc4a5e074) call msg from autoServer
Aug 17 00:04:15 sys [1318.1324]: SRV <3+error > NTP: Fail to sync NTP time(pool.ntp.org).
Aug 17 00:04:22 sys [1318.1324]: SRV <3+error > NTP: Fail to sync NTP time(cn.pool.ntp.org).

Other router phones for this client work just fine out of the office.

Thanks,

 

[Gingerr6]

SIP ALG springs to mind on his router....

 

[Gingerr6]

Also I would factory reset the phone once at home, it should then reprovison.
Make sure it's on the most recent supported FW.
And I know you've made sure his IP is not blocked.

 

[SteveITS]

I will ask about SIP ALG, thanks. However I wouldn't think that would block NTP access...?

We did factory reset it at home, I left that part out.

 

[TheodorosG_3CX]

On the remote location you have tried to factory reset and reprovision?
Also the NTP error means that the phone is not able to sync time which is not directly related but can indicate connectivity issues.

 

[SteveITS]

Yes we factory reset it and it provisioned only when it was connected elsewhere/in the office.

I don’t understand why provisioning or NTP fails but ping/DNS works.

I don’t think it’s a 3CX issue, I’m just looking for ideas.

 

[TheodorosG_3CX]

Just to clarify, are you able to reach the FQDN from this location?

 

[SteveITS]

Just to clarify, are you able to reach the FQDN from this location?

Yes, in a browser.

Interestingly, last night at 10:58 pm ET we received an alert that this phone/SBC was Up, and a Down alert 3 minutes later. It seems unlikely he was in the office. I have a question in to him about it but haven't heard back yet.

 

[SteveITS]

received an alert that this phone/SBC was Up, and a Down alert 3 minutes later

Our client says he restarted his ISP modem at that time. Which sounds again like a Comcast problem/block.

Not to digress, but I would have expected the Down alert to be sent after 5 minutes, not 3?

 

[TheodorosG_3CX]

Maybe this is also NTP related, however it is and issue with the ISP.

 

[SteveITS]

Following up on this, this person finally ended up swapping out their Comcast modem this week, and fixed the problem. Which was pretty much what we all thought, here, just strange powering off didn't fix it, if it was modem related.