Hi All

We've been trying out the CRS112-8P to power remote sites with a handful of 48V & 24V POE devices, but we keep running into an issue where the 24V devices don't want to power up. Whether the port is set to auto or forced on and low power, it keeps showing "low voltage" under interfaces. In the current setup I'm having a look at there is a Ubiquiti Nano being connected and according to the specs it's well within the power budget and should theoretically be able to run from the CRS, but no amount of fiddling has made it so. Upgraded the firmware to the latest but still no go (7.16.1).

Any ideas?

Check if power sources are correctly connected. 48V PSU to DCIn 48-57V and 24V PSU to 18-28V.

Wait, are you telling me we need to connect a 24V supply as well as a 48V one in order to do 24V POE?

Yes. CRS doesn't regulate voltage internally, it only passes whatever supplied. CRS112 is one of few MT devices with dual power input, allowing to select voltage for PoE-out. If one of inputs is missing, corresponding PoE-out voltage is missing as well.

All those years using the Ubiquiti ToughSwitch really spoiled me, 220V in and it automagically transforms that to 48 and 24V.

Come on Mik, you can do it too if you want, and 60W a port would make it all the more useful

Thanks guys

Indeed MT PoE offering is pretty inconsistent ... but there are a few rare devices which fare a tad better:

CRS328-24P-4S+ has internal dual-voltage power supply and offers per-port selectable voltage (24V passive PoE or 48V 802.3 af/at) ... unfortunately it has limit if around 24W per port

CRS320-8P-8B-4S+ is a recent addition to the fleet and offers 802.3 af/at/bt (POE++) ... the eight bt ports support whooping 80W while other 8 ports support modest 26W.

Oh yes, have used the CRS328 before, that's much more like it, and that 320 looks very promising. Really would be great though to get an 8 port equivalent as well. Can't always justify a full size switch.

MikroTik CSS610-8P-2S+IN is your friend then. I have 7x 48V real POE devices and one 24V Device (DISC Lite ac). Works fine!

Being an CSS, it only comes with SWOS lite. While SWOS is the better choice for most pure switches due to being much more userfriendly, the lack of Syslog can be annoying.

For the Switches actually needing dual Voltage supply I would be happy if MT would offer a Power source with 24V AND 48V or some sort of step-down-device from 48V to 24V you could just plug between the 48V supply. Or something like that.

... or some sort of step-down-device from 48V to 24V you could just plug between the 48V supply. Or something like that.

... like:

https://mikrotik.com/product/rbgpoe_con_hp