Sorry for posting here... Turns out Cloudflare's Firewall rules were causing this issue. I removed a firewall that was restricting access to a particular region and the issue resolved.
Virtual Programming Lab (plugin)
SSL issue just popped up on jailserver
Энэ мэтгэлцээн түгжигдсэн тул та цаашид хариулт өгөх боломжгүй