Solved by tom in post #2 
              
              
                The first 10 layers of vgg probably have 8 parameters (weight + bias for 4 conv layers) - those are the ones for the first param group when you split them -, the remaining part of vgg has 18 (9 more conv layers), bn1 and linear have 2 each (weight + bias). When you have a single parameter group (i.e…