EV Charging Station W-104 GX Communication Warning after Network Change and Firmware Update

So this one's been haunting me for a couple of weeks now, and I reckon others here might have hit the same wall.

Background: I run a Victron setup on my narrowboat — Cerbo GX, Venus OS Large (currently on v3.80), and a Victron EV Charging Station that I use to top up my little electric runaround when we're moored up with shore power. The whole lot talks over WiFi through a TP-Link mesh system I recently swapped in to get better coverage across the boat.

After updating the EVCS firmware and shifting to the new mesh network, I started getting a persistent W-104 GX Communication Warning on the charging station. The Cerbo can see the EVCS on the network — it shows up, pings fine — but the GX link itself keeps dropping and throwing that warning. Charging still works in standalone mode, but the integration is completely broken, which means no managed charging, no state-of-charge awareness from the BMS, nothing clever.

My suspicion is that the firmware update changed something about how the EVCS announces itself on the local network, and the mesh system's client isolation or DHCP handling is confusing things. I've tried giving both devices static IPs and double-checking that they're on the same 2.4 GHz band, but no joy yet.

Has anyone else seen this crop up after a firmware jump or a router change? I'm wondering whether there's a known fix — factory reset sequence, a specific Venus OS setting, or even just rolling back the EVCS firmware — before I go pulling cables and setting everything up from scratch again.

@CarlWalker this rings a bell from when I rewired my own narrowboat setup last autumn. After a firmware jump on Venus OS Large, my Cerbo GX completely lost its head about anything on the CAN-bus — threw communication warnings left, right and centre.

The culprit for me was the VE.Can profile resetting itself after the update. Worth checking in Remote Console under Settings > Services > VE.Can port — mine had silently reverted to a different profile, which meant the GX was essentially speaking a different dialect to everything downstream.

Also worth double-checking your EVCS device instance number hasn't shifted. A network change can reassign these, and the GX gets confused if it's expecting instance 0 and suddenly finds instance 1 sitting there.

What Venus OS version are you actually running? That detail might narrow it down considerably.

@CarlWalker welcome to the forum — good detailed first post, exactly the kind of thing that helps everyone.

One thing worth checking that often gets missed after a network change: the MQTT broker binding on the Cerbo. If your IP subnet shifted, Venus OS Large can end up shouting into the void — the W-104 GX communication warning is frequently that rather than anything more sinister.

Check VRM Portal ID is still resolving correctly under Remote Console → Settings → Services. Also confirm your ModbusTCP device list hasn't retained the old IP for any downstream devices.

What's your current Venus OS Large version? There were some known GX communication quirks around the 3.x branch that Victron quietly patched.

Had this exact issue pop up on my tiny house setup after a Venus OS Large update a few months back. The W-104 warning usually means the Cerbo's lost track of the EVCS on the network — worth checking whether the static IP you'd assigned pre-update has shifted back to DHCP after the firmware flash. Victron has a habit of resetting certain network configs during major version jumps.

In my case the fix was straightforward:

• Log into VRM portal
• Check the device list for duplicate or ghost EVCS entries
• Reassign the static IP via the Cerbo's networking menu

Also double-check your VE.Can termination if you're using that rather than Ethernet — a loose terminator threw me off for days before I spotted it.

@Del did you resolve yours in the end, or is it still intermittent?

Good shout from @LiFePO4Fan there. One thing worth checking that nobody's mentioned yet — after a network change, the Cerbo GX sometimes holds onto the old IP assignment for the EV charger in its device cache even after a reboot. Head into the Remote Console, go to Settings > Ethernet (or WiFi depending on your setup), and double-check the charger's IP hasn't shifted to a conflicting address on your new network range. I've seen the W-104 persist purely because of an IP conflict that looked fine on the surface. Also worth confirming your EVCS firmware version matches what Venus OS Large actually expects — Victron's compatibility matrix has caught me out before after a combined update. What firmware version are you currently running on both the charger and Venus OS? That'll help narrow it down considerably.