Hey! 
I recently purchased a UDM Pro to replace my old Cisco 2901 and I just thought, would the SFP+ on the UDM work with the SFP port on my switch (Cisco C3560-X) or is ethernet the only option.
Any input appreciated, and have a great day, thanks. 
If you have a 10gb modules for the Cisco (if supported), then you could get 10gb between both devices. If you don’t have one of the models that has the 10GB port, then gigabit is your only option.
So would I still be able to connect via the UDM’s SFP+ port to the 1gbs SFP port on the switch?
Generally speaking, yes, but… What you probably want to do is install a 1gb module into the SFP+ port. Something like a Cisco GLC-T has worked fine for me in my Mikrotik switch, but it also lists 1gb as a compatible mode. In general, SFP+ is backwards compatible to SFP modules but again check your specific device. That said, not sure about a direct connect cable, I think you should still use SFP modules and either copper or fiber to connect the two devices (which ever is cheaper, Multimode fiber cables are cheap).
I actually got in a fight with an Ebay seller about 1gb SFP into a Microtik CRS309-8s-1+ device (all SFP+), even after showing him that 1gb was supported and was supported by the device he shipped me, he still would not concede. The point of contention was that the module he shipped would not work in any of my devices. It wasn’t worth enough money to argue with this idiot, so I just ended up giving him the lowest feedback possible for being a twit and not even entertaining the fact that the module he sent was defective. It was even a Microtik branded module. I just jammed an extra Cisco GLC-T module in and went back to what I was doing.
Ah ok, interesting. I’ve just ordered a DAC cable off amazon so I’ll give that a try.
Thanks for the help and your story made me laugh
A DAC cable might or might not work - the limiting factor isn’t the UDMP, but the switch. DAC wasn’t part of the standard until SFP+, and even after that standard was released not all SFP equipment works with them. Either way, you will have to manually set the port on the UDMP to 1Gbps - auto speed on SFP+ ports only detects the local module (the end of the DAC), not the device at the far end of the connection.
If you wanted to try fiber, you would use 1Gb modules at both ends, and in that case shouldn’t need to manually set the speed.
It’s arriving today anyway. I’ll give it a go. If it doesn’t work, it’ll go straight into one of my poweredge’s instead