Even with the "best" viewer, settings can break. Here is the diagnostic flow from the intitle technical community:
The software must support multiple protocols simultaneously.
Best for: Customization and budget flexibility.
iSpy evolved into Agent DVR, a browser-based client that runs as a service. Because it is open source, every "client setting" is exposed to the user.
A: It includes connection timeout, stream preference, audio synchronization, recording retention, and hardware acceleration options.
After choosing your software from the list above, you need to optimize three specific client settings to achieve "best" performance.