Solved by ptrblck in post #4 
              
              
                Thanks for the explanation. 
I’m still unsure why you are rewrapping the layers in two nn.ModuleLists. I assume you are trying to use one nn.ModuleList for the “frozen” layers and another one for the ones, which should be fine tuned? 
Rewrapping the model would not be necessary, as it can break the …