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Talk about some problems related to can communication bus

Topic 1: isn't it said that the data transmission distance of the CAN bus is very far? 
So why are there all kinds of CAN data repeaters on the market? 
A: through the introduction of Baidu encyclopedia and other aspects, we know that the CAN bus can convey information as far as 10 kilometers away without relay help. Note that this distance is the furthest distance, not the most effective distance. What's the difference? we can illustrate it by comparing an example with a smartphone. 
Although today's smartphone no longer has the problem of stutter, but when it first appeared, the software and hardware were not up to standard. If you open a few more programs in the background at a time, then the phone will get hot and stutter sharply. Can you use it? 
It can be used, but it doesn't feel comfortable at all, and the experience is very poor. 
Then we go back to the CAN bus. At the data transmission position 10 kilometers away, the CAN data transmission speed has dropped to 5Kbps, which is basically close to no signal. Do you think this data transmission speed can still be applied to practical work? 
Therefore, we develop all kinds of CAN data repeaters, that is, we use other types of buses as the medium to make the effective data transmission distance of the CAN bus longer. As for what is the effective data transmission distance, it depends on your actual needs. You need at least 100Kbps, so just meet this data transmission speed. The farther the distance, the better. Do you understand?
Topic 2: why develop so many kinds of CAN data repeaters
A: the reason why we have developed so many kinds of CAN data repeaters is entirely based on our real needs. For example, if you want to extend the effective communication of CAN data for more than ten kilometers, it is best for you to choose an optical fiber to CAN repeater, because if you use optical fiber as a relay medium, the data transmission speed is very fast and the communication is real-time. 
At the same time, because the optical fiber line is generally wrapped in several layers of insulation, so its signal damage is very small, and its ability to resist external interference is relatively strong. 
Some students may ask that the fiber-to-CAN repeater is so awesome, so we all choose it for CAN data relay. 
This is bad. We said at the beginning that the reason why there are so many kinds of CAN repeaters is determined by reality. Although the optical fiber to CAN repeater has so many advantages, it is still a kind of wired information transmission, and the layout of its lines will be affected by the natural environment to a large extent. For example, it is not easy to set up some mountains and ravines. 
Therefore, if the above problems occur, we can use the WiFi to CAN repeater and use the WiFi wireless signal as the relay medium to achieve the extension of CAN data transmission. 
But similarly, the WiFi-to-CAN repeater also has its own shortcomings, such as how far the WiFi can transmit when the relay distance is close, which we all know. 
Moreover, because the WiFi signal is uncovered and exposed, it is easy to be interfered. 
Therefore, please decide which kind of CAN repeater is the most suitable according to the actual situation.