Any proxy settings on the machine should be automatically and explicitly applied on the stunnel configuration file and when a DevTunnel session is requested. When DevTunnel starts, stunnel.conf will be automatically updated to reflect the proxy settings of the machine, thus overriding the custom proxy settings.
Solution
Create an empty folder called C:\Program Files (x86)\DevTunnel\stunnel\config\skipproxy to prevent DevTunnel from overriding the custom proxy settings in stunnel.conf.
