Anyone else finding the new Victron Cerbo GX firmware update a bit hit and miss?

Updated mine to v3.40 last week on the boat and it's been giving me grief ever since. The VRM portal keeps dropping the connection every few hours — sometimes it's offline for 20 minutes, sometimes closer to two hours. Rolled back to v3.33 on my test setup ashore and it's solid as a rock, so it's definitely something in the new build. Running a Multiplus-II 3000, two 200Ah lithiums, and a 400W solar array through an SmartSolar 100/30.

Raised it on the Victron community forum and a few others are seeing similar, mostly on boats and vans with 4G routers rather than fixed broadband. I'm using a GL.iNet Slate AX with a Three SIM, and I wonder if it's something to do with how the new firmware handles reconnection after a brief signal drop. The MQTT keep-alive settings maybe? Bit above my head if I'm honest.

Has anyone managed to get v3.40 stable, or are you holding off on updating? Tempted to just stay on v3.33 until Victron push a hotfix, but I don't want to miss out if there's a proper fix in the newer build.

PartnerConvert | 📍 Yorkshire Dales | ⚡ Off-grid since 2019

@CoastalCruiser Ah, commiserations — I saw a few grumbles about v3.40 over on the Victron Community forum too. Worth checking whether it's specifically the VRM reporting interval that's gone wonky rather than the actual connection dropping. A few people found that reverting the interval setting to default (15 minutes) cleared up the phantom disconnects even without rolling back the firmware.

Also, are you on WiFi or the built-in Ethernet? Marine environments can be brutal for WiFi stability anyway, so if you haven't already, try a hardwired connection to rule that out before blaming the firmware entirely.

Victron are usually pretty responsive — logging a ticket directly with them with your VRM ID attached tends to get a proper response within a day or two in my experience.

VM_Solar | 📍 South Wales | ⚡ Off-grid since 2016

@CoastalCruiser I'd check whether it's specifically the VRM connection dropping or whether the Cerbo itself is losing network. Worth SSHing in and watching the logs in real time — tail -f /var/log/messages can reveal a lot. I've seen a few reports on the Victron Community forum suggesting the v3.40 build has some quirks with certain WiFi dongles losing their DHCP lease. If you're on WiFi rather than ethernet, try a static IP assignment and see if that stabilises things. Also worth checking whether venus-platform is restarting periodically. If a rollback to v3.30 sorts it, that'd confirm it's firmware-related rather than something hardware-side. Victron are usually pretty responsive on their community forum too — might be worth logging it there with your GX serial number.

OffGridAlan | 📍 Derbyshire Peak District | ⚡ Off-grid since 2017

@CoastalCruiser Had similar bother with mine after v3.40 — though I'm on a static setup rather than a boat so can rule out any marine-specific gremlins. What I noticed was the MQTT broker seemed to be the culprit rather than the VRM connection itself. Worth checking your Cerbo's system logs via the local console to see if there's anything throwing errors around the same timestamps as the dropouts. Also, have you got remote support enabled? I'd be tempted to roll back to v3.00 temporarily while Victron iron out the wrinkles — the Victron Community forum has a few threads about this already and one of the devs was active on there a couple of days ago acknowledging the issue. Fingers crossed a hotfix isn't far off.

Pete1994 | 📍 Array | ⚡ Cabin / Static Caravan / Shepherd's Hut

Mine's still on v3.31 and the shepherd's hut setup hasn't missed a beat — sometimes being a boring late adopter is genuinely a personality trait worth having. 🐑

Geoff1991 | 📍 Cambridgeshire Fens | ⚡ Off-grid since 2021

@CoastalCruiser Mine's been rock solid on v3.40 if I'm honest, but I'm running it in a static setup rather than a marine environment — worth considering whether the connection drops might be temperature or vibration related rather than purely firmware. That said, I did notice the MQTT broker behaviour changed slightly with this update, which could potentially cause VRM to lose its session intermittently. Have you checked under Settings > VRM online portal and looked at whether the "Last contact" timestamp is consistently resetting? Also worth trying a full reboot of your router alongside the Cerbo rather than just the Cerbo alone — had a mate with a similar issue and that sorted it. Victron's community forum has a dedicated thread on v3.40 issues that's worth a read too.

GazJones | 📍 North Yorkshire Dales | ⚡ Off-grid since 2019

Interesting one this. I updated to v3.40 a fortnight ago on my cabin setup and the VRM connection has been fine, but I have noticed the MPPT charging profile acting a bit oddly — absorption stage cutting short on a couple of occasions for no obvious reason. Checked the settings and nothing had changed, so I suspect the firmware tweaked something under the hood. Worth keeping an eye on your charge logs @CoastalCruiser, especially if you're relying on full charges before heading out. I've raised it on the Victron Community forum and someone there suggested checking whether the "has DC system" setting got toggled during the update — apparently that's caught a few people out. Might be worth a look before rolling back entirely.

BlownFuse | 📍 Array | ⚡ Static Caravan / EV Charging

Worth checking whether the VRM dropouts correlate with your EV charging cycles — I noticed on my static caravan setup that when the Victron MultiPlus ramps up for charging, something in v3.40 seems to struggle with the MQTT keepalive. Check Settings > VRM Online Portal > Last Error on the Cerbo itself.

Also, are you on WiFi or LAN? I've seen reports that v3.40 changed something in the WiFi reconnect logic. Wired connection apparently sidesteps the issue entirely. Victron community forum has a thread specifically on this — worth cross-referencing before rolling back.