Hi Vipul,
The problems I found (and fixed!) were actually related to filter center frequencies, bandwidths and making sure each component has the correct bit rate parameter.
For example, you changed the User Defined Bit Sequence Generators to a manual value of 10 GHz, so changing the global parameter Bit rate did not change the speed. Generally it is a better idea to keep all the components scripted to the global value of “Bit rate” which will make sure each component is updated automatically with the correct bit rate.
Furthermore, the WDM Mux need to be updated with a new channel bandwidth of 40 GHz other wise the signal will not be transmitted properly. This is also the case for the Gaussian Optical Filter at the receiver. Center frequency should be changed to 1540 nm and bandwidth set to 40 GHz.
I made the changes to the project file attached.
Cheers!