I've installed unifi controller sw on my Pi4 and managed to start the service, but when I connect the Pi via Ethernet cable to the switch, there is no internet connection. When I connect Pi directly into the ISP modem (It has 4 ethernet ports) the internet connection works, but when I connect it to the PoE switch from UniFi Pi doesn't detect ethernet connection*. The structure of the network is described in the picture but to explain little bit. From ISP there is DSL cable into the modem provided by ISP with 4 ethernet port. From this I've made ethernet connection to UniFi USG modem, leading into PoE Switch from UniFi. The Pi is then connected to switch wit UniFi controller. This setup should work according to my research.

Have I made some critical error in the "network" location of the Pi? What do I miss here?

Is the ethernet port on my Pi somehow bugged and I need to reinstall something?

Do you need more informations?

*FYI: Currently my Pi doesn't have PoE hub, because I have it powered over USB-C. PoE Hub is in plan in upcoming weeks.

Thank you in advance! Network structure

  • You have "installed unifi controller sw" on the RasPi. "The Pi is then connected to switch wit UniFi controller". Is the UniFi controller a program or a piece of hardware? Why do have to use the UniFi devices? What does "USG" mean?
    – Ingo
    Jul 2, 2021 at 22:06
  • @Ingo UniFi controller is a program to manage Ubuquiti switches, gateways and access points. It provides a "software defined nework"-like option for the network. The USG is the "Unifi Security Gateway",, the component in Unifi networks that acts as the central Layer-3 point. You can buy the software running on a (relatively expensive) propriety device, but Ubiqiti also distributes a version that can be run on a raspberry Pi. Jul 3, 2021 at 17:27
  • Thanks for updating me. You write "When I connect Pi directly into the ISP modem (It has 4 ethernet ports) the internet connection works". So It is very likely that the problem lies with the Unifi devices and isn't a problem with Raspberry Pi (and asking on the wrong site?).
    – Ingo
    Jul 3, 2021 at 19:46
  • @Ingo Hello, yes, that might be true, I just want to eliminate where the issue might be and raspberry was my first idea. Anyway it seems that I might even reconsider the current RasPi setup and run the controller in the docker which I've never done. Jul 6, 2021 at 8:29

1 Answer 1


This is - for the network part - a fairly standard set-up. There is quite a bit of information lacking, so I will give a strategy to determine the problem. It is too long for a comment, therefore it is posted as an answer.

First the physical connection. My Unifi switch has lights next to the connectors. If yours does too: do they light up when you make the connection? On the Pi, does the leds indicate connection (simplest test: do the leds change when you connect/disconnect)?

If this fails, use a new cable. Connect to a different port of the switch. You might try to connect the Pi directly via ethernet cable to a PC to see if the Pi is not broken.

I don't exactly know what you mean by "Pi doesn't detect ethernet connection".

If you ask ip addr, is the ethernet there? Does it have an IP address? If not: who hands-out the IP addresses in your set-up? What is the IP address of the USG at the LAN-side? Can you give the Pi a fixed IP address that is in the subnet of the LAN side of the USG?

Do the PC and work PC have Internet? How did they get their addresses?

  • Thanks for the response 1. Physical connection doesn't light up on switch or on Pi when it is connected. But it does light up for other devices connected (Desktop PC, laptop, APs). My assumption is it is really issue between Pi and the switch 2. Cables are okay, I've even crimped new ones to test this. It doesn't matter which port I use, everything is same. 3. Pi doesn't detect ethernet connection means, that I see "eth0 link is down" when connected to the switch. 4. I've made the pi static IP with USG has but I cannot access it because the eth link is down Jul 6, 2021 at 9:15
  • My current ISP modem/router has address of and this one is probably handing the IPs (DHCP is there enabled). For now, until the network works, I am connected to ISP directly. Jul 6, 2021 at 9:17
  • I run basically the same set-up as you described (16 port switch in stead of 4 ports). It is strange that the Pi does not connect to the Unifi switch, but works when connected to the ISP modem. Unless you made provisions, you shouldn't be able to manage the USG from the WAN side though. Jul 6, 2021 at 11:09

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