As with many computer-related issues there are countless possible causes, but I doubt that power quality is a factor in this case.
If a wireless link is involved, as suggested above interference on the channel that is being used is certainly a possibility.
What specific make and model is the computer? Does it have a mechanical hard drive or an SSD? Is the music stored on the internal drive that is utilized by Windows and the server program, or on a second internal drive, or on an external drive?
Also, what anti-virus program are you using, and have you tried temporarily disabling it? Some anti-virus programs can slow a computer significantly.
Also, if you already haven't, under the Start icon/Settings/Update and Security/Advanced Options/Choose How Updates are Delivered, change the default setting of "on" to "off." Otherwise, as stated on that page, "your PC may also send parts of previously downloaded Windows updates and apps to PCs on your local network, or PCs ON THE INTERNET" [emphasis added], which among other conceivable issues may intermittently slow down your computer.
Finally, your reference to "the last 2 months" brings to mind that the major "Anniversary Update" to Windows 10 was probably automatically installed in your computer during the month of August. If the computer and DAC combo was working properly prior to that time the Anniversary Update, which caused a variety of problems for many Windows 10 users, may have been a factor.
Regards,
-- Al
