Hello,

I recommend maybe change connection ID to have different one for send and different for receive. _C blocks are in this case independed blocks that use own internal system of functionality with own connection mechanism so different connection ID is expected here. I recommend also take to account that in case you set there inside TRCV connection definition so external Client have defined exact Port, it need have it defined because then your Server will refuse it logically.

What I can also recommend, you can better after each download to PLCs better to turn OFF/ON specific PLC to have all good initialized and working.