If your based in UK, it appears to be dependant on which ISP you have but there's a routing issue into CDN77 cdn.battleye.com is hosted on CDN77's UK London range and BT is currently black-holing it — TCP to it just times out, DNS is fine. a workround some people have used is a VPN as Routing your traffic through a Virtual Private Network (VPN) as this bypasses the broken BT-to-CDN77 network path completely. GeForce Now is also an option as appears to be connected to different back-end infrastructure in the UK. So don't rush to reinstall D2 as fix (as I did)...hopefully will get fixed soon by BT but likely after the Bank Holiday weekend., as it's intermittent - sometimes it's fine, connected fine around 11pm UK yesterday but currently fails connection to Battleye this afternoon