Hi @sea_Fire,
try net.linear[0]. The Sequential model is stored under the attribute linear in the Network class. Modules in a Sequential can either be selected by slicing or sometimes if there is a name given for the module by accessing the attribute via the name .
Here an example from the docs:
# Example of using Sequential
model = nn.Sequential(
          nn.Conv2d(1,20,5),
          nn.ReLU(),
          nn.Conv2d(20,64,5),
          nn.ReLU()
        )
print(model)
print(model[0])
# Example of using Sequential with OrderedDict
model = nn.Sequential(OrderedDict([
          ('conv1', nn.Conv2d(1,20,5)),
          ('relu1', nn.ReLU()),
          ('conv2', nn.Conv2d(20,64,5)),
          ('relu2', nn.ReLU())
        ]))
print(model)
print(model[0], model.conv1)