How to fix ERR_SSL_PROTOCOL_ERROR for only one specific site

Working on a site for a client, and for some reason I keep getting the "can't provide a secure connection" error in ALL browsers. Everyone outside me seems to see it fine. If I log in to my work computer with a VPN, it works fine. I've look at tons of articles on this error. Yes, my time is set correct, I've cleared my cache and so forth. I even tried copying over the SSL cert to my login keychain and select trust always, and this didn't work. It seems like browsers have been updated and they don't allow you to "trust anyway" anymore. This is my friend's company, it has a valid certificate and I know the site is fine. I need to allow this site to work in order to get my work done. I'm on a late 2013 iMac running Catalina 10.15.1.