Schindler error code 3603

Hi everyone ! Does anyone solved this error code? I know what that code means and i checked everything with this error code but nothing helps, when the elevator stops and shows this code i just do a reset and it runs about half a day and then i need to repeat again the reset.

are you an elevator mechanic or representative of the building?

3603 E_BIOBUS_NODE_DEAD
During operation the communication to a bus node (e.g.
landing operating panel) has failed.Note, this error occurs
every time the communication got lost to a single bus node.
C1:Bad connection to any bus node (e.g. landing operating
panel)
A1:Check generally bus wiring. Check bus connector on
controller main board and at all bus nodes.

Hi i work in one elevator maintenance company, we have different kinds of elevators, but i do know more about kone elevators, than others. I also was a fitter in kone and orona. I checked everything what that fault suggest, but nothing helps.