I have been using the Modbus TCP Slave for quite some time now. Since I upgraded from firmware version RUT9_R_00.07.02.4 to the latest one: RUT9_R_00.07.04, I have issues with the Modbus TCP Slave and actually only with the register address 137 "Digital galvanically isolated input (DIN2) state" which is not updated anymore...
I tested this on two other RUT955 routers that I also upgraded to the latest firmware version and still the same issue. I precise that I don't seem to have the same issue with other registers; I can still write on register 201 "Galvanically isolated open collector output status" and read 201 "Galvanically isolated open collector output status".
Finally, after upgrading to the latest firmware version, which is unfortunately not usable for me, I downgraded to the following:
RUT9_R_00.07.04 -> Not OK !
RUT9_R_00.07.03.3 -> Not OK !
RUT9_R_00.07.03 -> Not OK !
RUT9_R_00.07.02.7 -> OK !
RUT9_R_00.07.02.4 -> OK !
Therefore, it seems like something is wrong since the RUT9_R_00.07.03 version... (again, that was tested on three routers with the same behavior).
Could you please investigate this and tell me if I missed something.