Exporting ResNet to ONNX and TRT

I trained a ResNet 18 with 6 classes and it works really great so far.
Now I would like to export it, so I can use it on a Nvidia Jetson.

I don’t want to install fastai on the Jetson, as I is quite complex as I found out.
So I exported the model to ONNX with


Then I try to convert it to a TRT engine right on the Jetson with onnx2trt, but I get the following error:

Input filename:   opset11.onnx
ONNX IR version:  0.0.6
Opset version:    11
Producer name:    pytorch
Producer version: 1.7
Model version:    0
Doc string:
Parsing model
[2020-10-20 09:49:21 WARNING] [TRT]/home/nvidia/git/onnx-tensorrt/onnx2trt_utils.cpp:220: Your ONNX model has been generated with INT64 weights, while TensorRT does not natively support INT64. Attempting to cast down to INT32.
[2020-10-20 09:49:21   ERROR] (Unnamed Layer* 76) [Shuffle]: at most one dimension may be inferred
While parsing node number 75 [BatchNormalization -> "210"]:
ERROR: /home/nvidia/git/onnx-tensorrt/onnx2trt_utils.cpp:1498 In function scaleHelper:
[8] Assertion failed: dims.nbDims == 4 || dims.nbDims == 5

Do you have any suggestions?