Intro
DisplayLink itself is a free software, but purchasing a docking station that supports this software is not cheap (around $100). After using it for a year, I found that it is not a user-friendly Mac multi-screen tool.
Details
My method of use is to connect two screens and work with my Mac closed, which is the most basic way of multi-screen work.
From the beginning, a problem arose: if I don't connect the power cord, DisplayLink stops working when the Mac is closed, and I have to connect the power cord in order to use it with the Mac closed.
During use, DisplayLink's performance is also unstable. For example, after the Mac goes into sleep mode, the software may stop working and I have to manually open the Mac and restart the software in order to continue using it with the Mac closed. Sometimes, I even need to open the process manager and force a restart, which is very inconvenient.
Discussion
Mac OS's native external multi-screen functionality has many limitations, possibly due to the closed-loop business model protecting the desktop product line. However, regardless of the reasons, it is still a poorly designed and user experience. Hopefully, in the future, there will be better and more stable solutions available.