Can't access www.evite.com

Question

I can't seem to access www.evite.com on any device on my network. Things I've tried: 
 
 Setting up an exception for evite.com to bypass HTTPS decryption 
 Allow invalid certificates 
 Put my devices on a firewall rule that bypasses all scanning and policies 
 
 When I disconnect from my network and use cellular data, I can access the website just fine so I suspect it's something to do with Sophos XG. The error I get in Google Chrome: 
 
 This page isn&rsquo;t working 
 www.evite.com didn&rsquo;t send any data. 
 ERR_EMPTY_RESPONSE

shred · Accepted Answer

Turns out it was Pi-hole (DNS server) causing this. I tried disabling Pi-hole when I had this issue a few days ago but I still couldn't access the site leading me to believe it was Sophos XG (since it worked fine on cellular). For whatever reason, I tried it again today with Pi-hole disabled and I was able to access the site. Once I enabled Pi-hole, I could no longer access the site. Not sure why as I've added evite.com to my whitelist but this is obviously an issue with Pi-hole and not Sophos XG.