Welcome to the forum @Shiraho
Are you sending it to a modbus device or are you sending it to a modbus server on the same machine? If it is a modbus server what server is it?
Please select the two modbus nodes use the menu Export command to copy to the clipboard and paste here. When pasting use the </> button at the top of the edit window and paste the flow in. See this post for more details - How to share code or flow json
How often is the data being sent to the modbus node?
When it fails what does the status indicator under the Write node show?
