This isn't a question but rather a reporting of a potential driver conflict and a temporary workaround:
Main issue: the spacedesk server driver can interfere with laotop touch pad.
Laptop in question: Lenovo Leigon Y740 laptop running Windows 10.
The following steps can reproduce this issue nearly 100%:
1. Fresh install of spacedesk server (without prior installation, this is very important), everything works, compute can connect, touch pad works.
2. put computer to sleep (either manually put it to sleep or automatically letting it timeout)
3. upon wake up from sleep, the touchpad no longer works.
4. go to device manager, under "Human Interface Device", the "I2C HID Device" has a yellow icon with error message: I2C HID device cannot start (code 10)
5. Sometimes, disable, and re-enable the "I2C HID Device" can revive the touch pad, often times, it requires a restart of PC.
1. Uninstall spacedesk server from the laptop.
2. Problem with I2C HID device cannot start (code 10) goes away upon wake up from sleep.
3. reinstall spacedesk server again, touchpad problem comes back.
4. repeat step 1 to 3 a few times, eventually, the touchpad can no longer be fixed even with spacedesk server uninstalled.
5. at this point, the spacedesk client can longer detect spacedesk server.
6. the only solution i have found so far is for the above is, uninstall spacedesk server, go to device manager, enable "show hidden driver", and uninstall all hidden drivers under "Mice and other pointing devices", "Keyboards", and "Human Interface Devices",
7. and finally restart the computer, this will bring back the touchpad functionality.