I. Introduction  
II. Related IIoT Testbed Surveys  
III. Industrial IoT Overview  
IV. TSN-based IIoT Testbeds  
V. IEEE 802.15.4-based IIoT Testbeds  
VI. IEEE 802.11-based IIoT Testbeds  
VII. 5G-based IIoT Testbeds  
VIII. Suggestions and Practices  
IX. Conclusion