Trouble setting up Cerbo GX with Inverter and Charge controller

Been through almost exactly this commissioning headache with my shepherd's hut setup last spring, so this might save someone some time.

I had a Cerbo GX refusing to see my MPPT and a Multiplus II — both were sitting there connected via VE.Direct and VE.Bus respectively, showing nothing in the device list. Turned out I'd made two separate mistakes:

VE.Direct cables — I'd used a third-party cable from Amazon. Looked fine, but the Cerbo simply wouldn't enumerate the MPPT. Swapped for a genuine Victron cable and it appeared immediately. Lesson learned the expensive way.

VE.Bus / MPPT firmware — The Cerbo's firmware was newer than what the Multiplus II expected. Had to connect a laptop with VictronConnect via Bluetooth, update the Multiplus firmware over MK3-USB first, then let the Cerbo pick it up. Order of operations matters here.

A few things worth checking methodically:

• Confirm each device shows in VictronConnect independently before expecting the Cerbo to see it
• Check the Cerbo's VE.Direct port assignments under Settings → System Setup — easy to have the wrong port mapped
• With Dyness batteries specifically, you'll need the correct CAN-bus profile set (usually CANbus BMS, 500 kbit/s on the GX)
• Restart sequence matters: batteries on first, then inverter, then let the Cerbo initialise

Has anyone had issues with the 450/100 MPPT specifically on newer Cerbo firmware builds? I'm curious whether the larger controllers behave differently to the 100/20s I've used before.

@SuffolkExplorer mate, the classic "Cerbo playing dumb" — nine times out of ten it's VE.Direct cables swapped round or the VE.Bus termination resistor missing, which Victron buries in the manual somewhere between page 47 and "good luck finding it."

@SuffolkExplorer @AlanJones63 — worth adding that the Cerbo's VE.Can network needs proper termination at both ends, something that caught me out badly with my motorhome build. If you've got a SmartSolar MPPT with a VE.Can port and it's sitting at the end of the daisy chain without a 120Ω terminator plugged in, the whole bus goes unreliable — intermittent dropouts, devices appearing and disappearing in VRM. Victron's own documentation buries this rather than leading with it.

Also double-check your VE.Direct port assignments in Remote Console. The Cerbo has two VE.Direct ports and they're not interchangeable in terms of how certain firmware versions handle them — port 1 tends to be more stable for MPPT comms in my experience.

Firmware on the Cerbo itself matters too — anything below v2.80 had known discovery issues worth patching out first.

@LesWood78 raises a good point on the termination — though I'd add: double-check you haven't accidentally terminated both ends with the same physical terminator you've just shuffled round in frustration at 11pm while the rain hammers your boat roof. Not that I've done that. Twice.

Also worth checking **VRM Portal device

@BrianBrown all solid advice — and while you're poking around in VRM, check the firmware versions are consistent across your Victron kit, because a Cerbo on old firmware talking to a freshly updated Multiplus II is basically two people arguing in different languages at a party neither wanted to attend.