Over the years here have used Lantronix, Digi (serial servers, Edgeports and USB to ethernet) and Quatech servers for my automation.
IE: still have a Digi rack mounted 16 port serial / 4 port USB to USB device that I use for serial and USB connectivity to the automation server. (and Lantronix).
Had an issue with the Quatech servers which are no longer supported running in Linux.
I tried to build the Linux drivers for it with no luck at all.
One server here today is running Ubuntu 18.04 64 bit for Homeseer Pro and Oracle Windows 2016 server VB for some Windows only SAPI stuff (well now 5 voices used for TTS). I was able to load the old Quatech serial to ethernet drivers on the Windows server and can get to my Quatech serial devices via Windows and Ubuntu which works for me still utilizing the old W800 and Cheaper RFID stuff here.
For the Cheaper RFID stuff it is just local and no dependencies on smart phone technology. It is working 100% of the time.
The original configuration was putting the devices in the attic next to the antenna(s) and using Cat5e for the serial connection to the basement (attic==> second floor ==> main floor ==> basement server room). Put a Quatech server in the attic and it is working great these days.