IP-Phones looses connection

[EJL88]

Hello,

This issue is properly more related to the hardware setup than 3cx, but:
I have made a small setup with a 3cx installed on a server, with 20 phones connected to the system. For some reason 3-4 of these phones loses connection with the network or does not get an IP at all. If I do a restart of all the phones at the same time, some of the phones that didn't work before works, and some of those that worked does not. In total it is the same group of about 7 phones that has this issue.

I'm pretty sure it has something to do with noise, but if I connect a PC or one of the UniFi access point, it works just fine, but both the Grandstream 1615 and Fanvil X4 fails to get an IP

Setup:
Unifi 24 port Switch PoE+
CAT6 STP cables (Max length is 60m)
All cables tested and pass tests.
Grandstream 1615
Fanvil X4

The phones are installed in living containers, two in each.
The network cable going into the container is connected in a box with 2x 400V cables and a DC current fire alarm system, and just to make things funny, this is done in a stainless steel box.


We had an electrician that does network cable installations to have a look at it, and he tested it etc and concluded it could be the phones that were the issue because his PC worked just fine on the network. If I connect the phones with a short cable at the switch, they work just fine.

 

[BrenttG]

You might want to consult your DHCP configuration and see if you dont have enough IPs alloted and the phones are fighting over the last few available.

 

[EJL88]

You might want to consult your DHCP configuration and see if you dont have enough IPs alloted and the phones are fighting over the last few available.

Ah, forgot to mention:
The phones+server has its own subnet, and I have checked that there are enough leases available.

 

[Saqqara]

Are you running out of Poe power on the switch ?

Have you checked the poe settings for the port on the switch, comparing with one that works

Can you connect one of the phones to a normal switch , using a external power supply to the phone to see if this works.

 

[EJL88]

Are you running out of Poe power on the switch ?

Have you checked the poe settings for the port on the switch, comparing with one that works

Can you connect one of the phones to a normal switch, using an external power supply to the phone to see if this works.

Yes, I am using PoE+ on all the ports (checked the settings just to be sure) - The only other option is 24v, but it is my understanding that setting is not suited for the phones.

Will see if I have a dumb switch laying around and if I kept any of the power supplies from the phones, and test it tomorrow.

I just find it odd that PCs and the WiFi APs (APs also PoE+) can connect - Is there something different with PBX traffic? Or are the phones just more sensitive?

Thanks for the replies.

 

[JohnS_3CX]

If the phones have enough power to boot up and are not boot-looping then you are probably OK on power. The fact that they don't receive an IP is more related to the network side if things.

When a phone boots up it will send a multicast message which needs to reach your DHCP server. If perhaps there are switches along the way that don't allow this message to reach the destination then you might have to look into that part of the network (since there are enough free leases).

 

[EJL88]

If the phones have enough power to boot up and are not boot-looping then you are probably OK on power. The fact that they don't receive an IP is more related to the network side if things.

When a phone boots up it will send a multicast message which needs to reach your DHCP server. If perhaps there are switches along the way that don't allow this message to reach the destination then you might have to look into that part of the network (since there are enough free leases).

Sometimes, I can see the phones do get an IP but lose connection with the server shortly after.
The 24 port PoE switch is directly connected to the router, and no additional switches.

The more we fault find on it, the closer I get to the conclusion that it is noise. It is on a ship, and there is not a lot of space to run cables, so they all run along power lines and other cables. Just hoped the screen (STP cables) would have meant they would have worked.

Will the phones keep doing this multicast until it gets a reply? Or is there a max?

 

[JohnS_3CX]

Usually they will transmit at startup and then give up after a while until rebooted.

Since its on a ship, is everything properly grounded? Keep in mind that maritime VHF radio might overlap with the frequencies used by ethernet.

Regardless, if you don't have a tool to measure noise what you could do as an alternative test, is transfer files over the same cable and see what data throughput you get. If indeed there is noise then it would be normal to expect your transmission will be just a few megabits at best. There are a few tools out there that test LAN throughput and provide useful feedback to falsify the noise theory. Even calls would be impossible though, a few packets for DHCP negotiation are nothing compared to a constant G.711 audio stream

 

[BrenttG]

When a phone boots up it will send a multicast message which needs to reach your DHCP server. If

Think you mean broadcast, unless you have implemented RFC 2131 for MDHCP...

 

[JohnS_3CX]

Think you mean broadcast, unless you have implemented RFC 2131 for MDHCP...

I stand corrected sir