For reasons possibly related to our VPN or firewall, Mathematica would fail to open notebooks at startup, instead stalling out at the welcome screen.

I first attempted to correct this issue by clearing out my cache directories as instructed here:

https://support.wolfram.com/12464

however, this did not resolve the problem. When I contacted technical support, I was told that I need to set command line option

-pacletreadonly

but I wasn't instructed where exactly this needs to be added, and I can't find any online documentation. Could somebody please direct me to some resources on this (I'm working on a Windows OS, in case that's relevant)?