I've just switched on my system for the first time, but for some reason only my cerbo gx is showing on my device list, my shunt, inverter and batteries are not showing. I'm thinking I may have wired the cat5 plugs wrongly. Is there a place to find out how to make your own compatible ve can and bus cables? Or could something else be wrong?
I wired the cables as 1 to 1, 2 to 2 3 to 3 and so on.
Ve can are straight patch cables, so are ve bus.
The only ones that are different are the type a and type b.
What shunt do you have?
did you use a terminator in the ve can port?
Make sure you are in the correct ports. I have seen that as a common mistake.
It turns out that the self made network cable was obviously made bad, as I tried a pre made cable, and it's showing up now in my device list. I also fitted a pre made straight network cable to my multiplus ii and to tje can bus on the cerbo, but this is still not showing up. Any suggestions? 
MultiPlus-II (any MultiPlus or Quattro, actually) is VE.Bus, not VE.Can - it won't show up if it's not plugged into the correct port.
Have a look at the Cerbo manual for more information: https://www.victronenergy.com/media/pg/Cerbo_GX/en/connecting-victron-products.html#UUID-45296fbc-6298-b29c-2e54-7730edc3d313
UIf your batterys bms is compatible use an victron A or B can bus cable, see
https://www.victronenergy.com/live/battery_compatibility:start
And
https://www.victronenergy.com/live/battery_compatibility:can-bus_bms-cable
