System Configuration
- Cerbo GX
- Venus OS Large v3.80~27
- Victron EV Charging Station
- EVCS Firmware v2.05.5.2
- TP-Link Deco E4 Mesh Network
- Both devices connected via WiFi (2.4 GHz)
Problem Description
My EV Charging Station was previously connected to the Cerbo GX and worked correctly.
The following functions were working before:
- Battery State of Charge (SOC) displayed correctly
- Dynamic charging control
- GX communication active
- General integration with the Cerbo GX
Occasionally there were connection dropouts, but whenever the connection was established, everything worked as expected.
Recently I changed my home network from TP-Link Powerline/WiFi extenders to a TP-Link Deco E4 Mesh system.
At approximately the same time, the EV Charging Station received a firmware update and now shows a completely different user interface than before.
Since then the EV Charging Station reports:
W-104 GX Communication Warning
“Connection to GX device cannot be established.”
Current Configuration
Cerbo GX
- Venus OS Large v3.80~27
- MQTT enabled
- Modbus TCP Server enabled
- Remote Support enabled and online
- Connected to WiFi network “Pichl103TP”
- IP Address: 192.168.68.111
- VRM Portal connected and operational
- VRM Portal ID: c0619ab1e875
EV Charging Station
- Firmware v2.05.5.2
- Connected to WiFi network “Pichl103TP”
- IP Address: 192.168.68.104
- GX Communication enabled
- GX IP Address configured: 192.168.68.111
- VRM Portal ID configured: c0619ab1e875
Troubleshooting Already Performed
Network
- Replaced Powerline network with TP-Link Deco E4 Mesh
- Confirmed both devices are connected to the same SSID
- Confirmed both devices are connected to the same mesh node
- DHCP reservations configured
- Device Isolation disabled
- Fast Roaming disabled
- Both devices receive valid IP addresses
Cerbo GX
- Verified WiFi connection
- Verified VRM connection
- Verified Remote Support online
- Verified MQTT enabled
- Verified Modbus TCP enabled
- Rebooted Cerbo GX several times
EV Charging Station
- Rebooted multiple times
- GX Communication disabled and re-enabled
- Confirmed correct GX IP address
- Confirmed correct VRM Portal ID
- Performed complete factory reset
- Reconfigured WiFi from scratch
- Reconfigured GX settings from scratch
Modbus Scan
On the Cerbo GX:
- Modbus TCP Server enabled
- Modbus device scan performed multiple times
- No devices detected
- No stored Modbus devices present
Current Situation
Both devices appear healthy and connected:
- Cerbo GX online and visible in VRM
- EV Charging Station online and reachable via Bluetooth
- Same network
- Correct IP configuration
- Correct VRM Portal ID
However the EV Charging Station continuously reports:
W-104 GX Communication Warning
and cannot establish communication with the Cerbo GX.
Has anyone seen a similar issue after updating the EV Charging Station firmware or migrating to a Deco Mesh network?
Any ideas for additional diagnostics or known compatibility issues between EVCS v2.05.5.2 and Venus OS v3.80 would be greatly appreciated.
Update / Additional findings after further troubleshooting
Hello everyone,
here is an update after several additional hours of troubleshooting.
System
- Cerbo GX
- Venus OS Large v3.80~27
- Victron EV Charging Station
- EVCS firmware: v2.07 / 5.2
- TP-Link Mesh network (recently installed)
Original problem
Previously the EV Charging Station was successfully connected to the Cerbo GX and GX-controlled charging worked.
After installing a new TP-Link Mesh network and updating the EV Charging Station firmware on the same day, communication between the EV Charging Station and Cerbo GX stopped working.
Unfortunately, I cannot determine whether the problem is related to the Mesh installation or the EVCS firmware update because both changes were made at nearly the same time.
Current symptoms
EV Charging Station
When selecting Discover:
No GX devices were found. Please try again later.
When entering the GX IP address and VRM Portal ID manually and selecting Check:
Can’t connect to the GX device (192.168.68.111)
Network status
Cerbo GX
- Connected to WiFi
- IP address: 192.168.68.111
- Signal strength approx. 50%
- VRM connected
- Last contact: a few seconds
- VRM status: No error
EV Charging Station
- IP address: 192.168.68.104
- Same subnet as Cerbo GX
Connectivity tests
Ping from PC to Cerbo GX
ping 192.168.68.111
Result:
4 packets sent
4 packets received
0% packet loss
Ping from PC to EV Charging Station
ping 192.168.68.104
Result:
4 packets sent
4 packets received
0% packet loss
Both devices are reachable on the network.
Cerbo GX checks performed
Modbus TCP Server
Enabled.
Available Modbus Services
Visible and working.
Examples:
- Battery
- MultiPlus-II
- MPPT 450/100
- MPPT 450/200
- Temperature sensors
MQTT Access
Enabled.
VRM
- Connected
- No communication errors
- Portal ID matches EVCS configuration
Local GUI
Working.
Remote GUI via browser
Working.
I can open:
http://192.168.68.111
and access the Cerbo GX GUI without problems.
Additional tests
ARP table
Both devices appear correctly in the network:
192.168.68.111
192.168.68.104
PowerShell TCP test
Test-NetConnection 192.168.68.111 -Port 502
The command keeps waiting for a response and does not complete successfully.
I am not sure whether this is expected behaviour or whether port 502 is actually blocked.
Cerbo GX security settings
Local network security profile:
Unsecured
SSH disabled.
No access restrictions configured.
Modbus device scan
Cerbo GX:
- Automatic scan enabled
- Manual scan performed multiple times
Result:
No Modbus devices found
Observations
- Cerbo GX is online and fully operational.
- VRM communication works.
- Local GX GUI works.
- EV Charging Station can reach the network.
- Both devices are in the same subnet.
- IP connectivity exists.
- GX discovery fails.
- Manual GX connection fails.
- Problem started after EVCS firmware update and/or network change.
Question
Has anyone experienced a similar issue with:
- EV Charging Station firmware v2.07 / 5.2
- Venus OS Large v3.80~27
- GX discovery no longer working
- “No GX devices were found”
- “Can’t connect to GX device”
Has anybody solved this by:
- Downgrading EVCS firmware?
- Changing Venus OS version?
- Adjusting GX security settings?
- Disabling Mesh features (client isolation, roaming, multicast filtering, etc.)?
Any suggestions would be greatly appreciated.
Thank you! 
Thomas Hofbauer (Austria)
Important clarification: The EVCS is not visible in the VRM device list and cannot be controlled from VRM. However, the EVCS local dashboard does show battery SOC, PV power, grid power and inverter status from the Cerbo GX. So local read access from GX data works, but EVCS registration/control via VRM does not work.
SOLVED – EV Charging Station not found by GX / not visible in VRM after firmware update
I would like to provide a final update in case it helps others with the same issue.
Symptoms
After updating my Victron EV Charging Station and migrating my network to a new TP-Link Mesh system, the following problems appeared:
- EV Charging Station could not discover the GX device.
- “No GX devices were found. Please try again later.”
- EV Charging Station was not visible in the VRM Portal.
- EV Charging Station did not appear in the VRM device list.
- Remote control of the charger via VRM was no longer possible.
What was working
- Cerbo GX was online and connected to VRM.
- VRM Portal worked normally.
- Cerbo GX was reachable via IP address.
- Modbus TCP Server on the Cerbo GX was enabled.
- Ping between devices worked.
- TCP Port 502 on the Cerbo GX was reachable.
- The EV Charging Station could read battery SOC, PV power, grid power and inverter information from the GX device.
This proved that basic network communication between the EV Charging Station and Cerbo GX was working.
Solution
The solution was to manually add the Cerbo GX as a Modbus device in the EV Charging Station.
I entered the Cerbo GX IP address manually in the charger’s Modbus device configuration and added it as a Modbus device.
After doing this:
- Battery and system data were available correctly.
- Communication was restored.
- The EV Charging Station became visible again in VRM.
- Remote control via VRM worked again.
Additional Information
During troubleshooting, a new EV Charging Station firmware was released:
EV Charging Station firmware: v2.08
I cannot say with certainty whether the root cause was:
- the network migration to the TP-Link Mesh system,
- a firmware issue in the previous charger version,
- or a combination of both.
However, after updating and manually adding the GX device as a Modbus device, the system started working correctly again.
System Information
- Cerbo GX firmware: v3.80~27
- EV Charging Station firmware: v2.08
- Communication via Modbus TCP
- TP-Link Mesh Network
- Cerbo GX IP: 192.168.68.111
Thanks to everyone who contributed ideas and troubleshooting suggestions.