Although most operating systems were released long after PLS was retired, since it's just a service, this issue is probably not an related to the Operating System. It's more likely caused by interference from some other software running on the same machine. Usually it's simply virus protection software causing the issue. If you can't determine what is interacting to cause this issue, rebooting the server resolves the issue (for a while.) Here are some better long term options:
Uninstall then Re-install PLS. Make sure you are using the latest release 220.127.116.11.
Install the software on a different computer. It will run well on a Windows 10 workstation or better.
Install our current license manager software Altium Infrastructure Server (AIS) which obsoleted PLS. This Knowledge Base article has a comparison near the end. It indicates features that influence some customers to update their private license server software, and has all the information you need to download/install the latest version of either one (Both PLS and AIS can be installed on the same machine during your transition.)
Switch to On-Demand licensing. This is arguably the best option if your engineers are connected to the internet and have an AltiumLive account in your organization. You can have your license(s) converted to On-Demand type and let Altium maintain your license server in the cloud so you don't have to run one on site. Licenses can be managed from the same company dashboard used to manage user accounts. On-Demand type licenses allow your users to access licenses from anywhere with no need to VPN into your company’s network, and to work offline by roaming a license if needed. License type pricing has been restructured such that private server licenses are no longer less expensive than On-Demand licenses. Please contact your account manager to make this change. It usually takes about a day.