Ublock Origin causes DNS leak with VPN browser extensions, revealing my ISP. In order to use a VPN extension securely, I have to disable Ublock Origin. With 'DuckDuckgo Privacy Essentials' (https://addons.mozilla.org/en-US/firefox/addon/duckduckgo-for-firefox/), along with more restrictive browser settings (block 3rd part trackers, etc.), I'm adequately covered for tracking. All I need after that is an effective ad blocker and I found a great one called 'AdBlock for Firefox' (https://addons.mozilla.org/en-US/firefox/addon/adblock-for-firefox/) - which not only allows me to run a VPN browser extension securely along side of it, but it even blocks YouTube ads. Ublock Origin has not only become a problem, it no longer serves any useful purpose for me. Ublock Origin add-on removed.