SLZB Ultima 3 - Z-Wave stopped working, can´t get it to work anymore

[remcomeeder]

I have recently bought a SLZB Ultima 3 with the Z-Wave add-on.
At first it worktcp://192.168.50.206:9638ed perfectly fine and since I am new to the Z-Wave world I bought one Z-Wave device to do some tests.
Everything worked fine until a recent Home Assistant update after which Z-Wave completely stopped working for me.
Since I only have one device I decided to remove everything related to Z-Wave and tried to get it to work again but I can´t get it to work anymore.

I have first installed zwave-js-ui and I have configured the serial port as follows: tcp://192.168.50.206:9638 (correct IP address and port).
Even when everything is entered in the configuration (no configuration errors are reported) I keeps failing to start the driver.

2026-07-04 13:33:15.443 CNTRLR querying Serial API capabilities...
2026-07-04 13:33:15.444 DRIVER » [REQ] [GetSerialApiCapabilities]
2026-07-04 13:33:17.044 DRIVER » [REQ] [GetSerialApiCapabilities]
2026-07-04 13:33:18.647 DRIVER » [REQ] [GetSerialApiCapabilities]
2026-07-04 13:33:20.249 DRIVER Failed to initialize the driver: ZWaveError: Timeout while waiting for an ACK
from the controller (ZW0200)
at Driver.sendMessage (file:///opt/node_modules/zwave-js/src/lib/driver/Dr
iver.ts:7267:23)
at ZWaveController.queryCapabilities (file:///opt/node_modules/zwave-js/sr
c/lib/controller/Controller.ts:1075:37)
at Driver.initializeControllerAndNodes (file:///opt/node_modules/zwave-js/
src/lib/driver/Driver.ts:2048:46)
at Immediate. (file:///opt/node_modules/zwave-js/src/lib/driver
/Driver.ts:1760:16)
2026-07-04 13:33:20.250 INFO Z-WAVE: Restarting client in 15 seconds, retry 49

[robertsLando]

Not sure as the expert in this field is @AlCalzone but try to disable soft reset in settings

[AlCalzone]

There is simply no response being received at all. Do you have any way to see if the controller sends anything back over the network? Maybe a router-level packet trace?