The current Fiddler Everywhere rules do not allow you to simulate modem like you could do with Fiddler Classic. 

https://www.telerik.com/forums/can-fiddler-be-used-to-throttle-an-android%27s-or-iphone%27s-network-connections

I want this functionality brought back so I can do things like we had in the old Fiddler:

Fiddler includes a Custom Rules Engine that can simulate throttling. To enable it go to Rules -> Customize Rules... or (CTRL + R) and set the m_SimulateModem variable to true. 

The script that executes when this is true is as follows:

if (m_SimulateModem) {
    // Delay sends by 300ms per KB uploaded.
    oSession["request-trickle-delay"] = "300"; 
    // Delay receives by 150ms per KB downloaded.
    oSession["response-trickle-delay"] = "150"; 
}

I have tried Delay Request but it's not the same:

After installing and launching Fiddler Everywhere 1.6.0 on macOS Big Sur 11.2.3, I am presented with the account login window. No matter if i attempt to create a new account or sign into an existing account, i'm presented with a "Network error" message.

Looking in ~/Library/Application\ Support/Fiddler\ Everywhere/Logs/electron.log, I see:

[2021-04-14 08:53:53:762] [info] Setting the following proxy settings to the main window: {"pacScript":"http://<redacted>","proxyRules":null,"proxyBypassRules":"localhost;127.0.0.1;*.local;169.254/16"}

[2021-04-14 08:53:55:831] [error] Error: Error: net::ERR_MANDATORY_PROXY_CONFIGURATION_FAILED
    at SimpleURLLoaderWrapper.<anonymous> (electron/js2c/browser_init.js:105:6497)
    at SimpleURLLoaderWrapper.emit (events.js:315:20)

[2021-04-14 08:53:55:832] [error] Error: net::ERR_MANDATORY_PROXY_CONFIGURATION_FAILED

After looking at the electron log for a bit, and trying to login, the gui now reports: "No internet access and it seems you have a proxy set. Check if it is correct in your OS settings and restart the application after that."

Yes, it is true I have a PAC url. I am also not on the network currently that uses that PAC url. Every other network-using app seems to deal with this ok (browsers, office suite, file sync, etc.).

I request that you handle the PAC url like every other app out there and test for reachability and stand down (i.e. don't use proxy) if not reachable.