I first had the udp-solution running with my goodwe inverter ET 15K-ET and then switched to modbus/tcp. Both were stable and reliable.
- via udp with the python library (Connecting Goodwe Solar Panel Inverter Directly to Openhab - #20 by Larsen ): The downside for me was that the polling interval was only every 3 minutes and that I was not able to do forced charging of the battery.
- via modbus-tcp: This was only possible after installing the wifi 2.0 module, but it was worth it: Direct connection via modbus binding, forced charging etc (lots of info here but in german: https://www.photovoltaikforum.com/thread/186135-goodwe-gw10k-et-sammelthread/)