I *finally* got somewhere! I did, in fact, need to re-enable the browser opening (Run > Set Project Configuration > Customize > Advanced > Default) so that the browser opens with "?XDEBUG_SESSION_START=session name" at the end of the address. I previously had "Do Not Open Web Browser" because of these instructions. Once I re-enabled the Web Browser, it worked and connected. When I had attempted those instructions before (and didn't disable the web browser thing), I had configurations for xdebug 2, but I needed xdebug 3. I had changed to xdebug 3, but it didn't work until I enabled the web browser opening again. Now, upon the web browser opening, I'm getting "504 Gateway Time-out." But at least I can connect remotely with xdebug now!