UBNT Edgeswitch not getting DHCP address

Note: At this point I have no solution, this is just me documenting the problem. If I find an answer I’ll update the blog. I just wanted people to know they’re not going mad.

Today I received the ES-8-150W Ubiquiti EdgeSwitch I had ordered to run my new home lab. It is a very affordable, fully managed, low power switch that supports 802.3at (or PoE+).

This is my first home lab so the ES-8-150W switch, a SYS-E200-8D microserver, and a couple of 3502’s are as complex as it gets. The plan is to run the microserver’s multiple NIC’s and the AP’s into the switch. For ease of management I want to hook the switch up to my home internet router, an Asus RT-AC68U running Merlin’s customised version of AsusWRT.

The “hardest” part of the base setup, the microserver IPMI interface and the ESXi server, was straightforward and as expected. The “easy” part was supposed to be plugging the switch into the router and letting it grab the management IP address I had reserved for it. The instructions claim it will attempt to grab a DHCP address and then default to 192.168.1.2 if it fails.

Well, that did not happen.

As mentioned, the IPMI interface and the ESXi server had taken the IP addresses reserved for them, so I know the router’s DHCP is working. But the switch hadn’t taken any DHCP address, it had fallen back to the 192.168.1.2 address (which was on a different subnet to the router).

I had been running a console connection to the switch the whole time out of curiosity to see the start up process (now I think about it I wonder if this contributed to the problem…?), so I tried messing around in the CLI to force it to take a DHCP address, but as this was the first time I touched a UBNT product I couldn’t figure it out.

After digging around for more time than was sensible I decided just to access the web interface using the fall back address of 192.168.1.2 to see if I could force it to use DHCP. To do this I plugged a notebook into the switch. I knew I was going to have to statically assign an IP in the right subnet to the notebook but I thought I’d quickly check to see if had any IP. To add to the frustration and confusion the notebook had successfully received an IP address from the router through the switch port.

Once in the web interface of the switch I was able to set it to DHCP and it finally got the address it was supposed to from the router.

My conclusion is that the switch never tried to get any address from the router, which cost me time. I have a really busy couple of weeks coming up and don’t want to waste much more time on this, but I think I will log a ticket with UBNT and see if they can explain. If I find a solution I’ll update the blog to help others.

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