I have some RUT240 modems. Until firmware 1.11.3 I have no problem reading registers with modbus tcp. After upgrading to version 1.12.2 , every time I read a register it says "TCP/IP connection terminated". It read the value, but after show this error. Until fw 11.3, I didn't have this problem. I'm using "Modscan32" program, but also using Siemens plc I have the same problem, now.