Network jack wall port 'burnt' after plugging in Unifi Lite 8 PoE Swtich

I have run into a weird issue with setting up an internal network in a shared office building. Please bear with me. I need to provide detail. First, a little backstory…I have a client that is an Insurance agent for a worldwide company (not mentioning names). He has a staff of about 5 people. and occupies about 4 offices in a large corporate office building where other non-related agents have their own offices. TMK they all share the network, no segmentation or VLans. In one of my client’s offices, more than one staff person occupies that office and they need to share resources: NAS, Printer, etc. Oh…and most of those offices have only one wall network jack. One other thing, all staff use notebooks and wifi, on the same network, but not hardwired. About 3 years ago, I set up an 8 port Netgear switch, connected the NAS, printer, and an Intel NUC (I use to remote in when I need to access to the internal network). That all worked fine for a few years until late last year, when the local tech management changed all the phones to VoIP. And of course with one network jack in the office, what can you do. Being as the original Netgear switch did not have PoE, I purchased a Unifi Lite 8 PoE (4 port PoE, 4 non-PoE). One other thing…there is a local in-building person who ‘handles’ the technical issues 'plugging / unplugging cables or the like). She only knows what outside tech tells her to do. Nothing about the inner workings of the network, or being able to recycle a switch port, etc.

At the end of last year, right after they had deployed the IP phones, I think they were still working some bugs out.

  1. I put in an Unifi Lite 8 so it can power the phone.
  2. Plug that Lite 8 to the to wall (using port 8…no PoE), plug the phone into one of the PoE ports. I set up LLDP-Med. to pass whatever setup they had to the phone.
  3. Used other ports for the NAS, Printer, NUC (typically 5 thu 7-non-PoE).
  4. I could never get that to work correctly. At that point phone was on but no connection (and I don’t remember if it was active before I started), and the other devices would not get address.
  5. I tried multiple variations, plugging the switch into the wall jack, or to the computer jack on the phone. Never could get it to function as expected. Either the phone would not connect, or other equipment would not get IP addressing, etc.
  6. In the end that day, with just the phone plugged back in, it would power up, but would not connect to the VoIP system.
  7. A few days later in-building management person stated that I had ‘burnt’ a port and they had to replace the wall jack…(note, there is also internal building remodeling type activities going on at the time, and she stated that before I was there, they had ‘burnt’ other ports)…hmm
  8. We decided to leave it alone for a while, since the agent and staff would be moving to different offices in the same building. So we would tackle it then.

On to today (April 2025):

  1. The one office I am working in has one wall jack, with the IP phone plugged in. Phone was working.
  2. I plugged my notebook into the computer connection on phone, got an IP, could browse the Internet, etc.
  3. I then plugged the Unifi switch (port 8) into the computer jack on the IP phone, thought I was going to get somewhere.
  4. Seemingly after that, I looked at the phone, and while still powered up, it stated no network connection.
  5. I unplugged both connections from back of phone,and replugged the cable (PoE) from the wall jack back to the phone in attempt to reboot phone, and phone would not power on. I tried other cables.
  6. Long story short, I now get nothing out of the wall jack.
  7. Had to call outside building management tech support (have to go thru corporate and India, first). Someone will have to check the port in that office. Awaiting feedback.

Sorry for the long-winded explanation, but i wanted to put out all the details.
Never had such a scenario before. I hope someone can enlighten me.

Thanks for listening
Lonnie

POE has a safety in it that should prevent it from “burning out” a port.

But a little bit of water will give you a bad day, at least on some of the cameras I’ve worked with. Not a burned like sudden short, but this gradual electrolytic corrosion that eventually forms a short.