Most firewall and anti-virus (AV) software is compatible with Paperspace. We recommend Microsoft Security Essentials or Windows Defender as they are powerful and free to use. If you plan on modifying anything on your VM, we highly recommend taking a Snapshot first.
If using a third-party firewall/AV application, make an exception for paperspace_service.exe and ps_agent.exe within your Paperspace machine to ensure you don't lose access.
You must configure your firewall to allow traffic over these ports:
9980 (Video stream)
5900 & 22 (Linux) (this does not expose your machine as Paperspace filters this traffic from the public Internet)
Note: Be sure to keep the inbound connections blocked using specific rules. Don't set this to "Block all connections." The default settings within the Windows firewall are right (as depicted below).