Thank you.
Indeed connectivity restored today several hours ago and cert renewed successfully.
However, I did literally nothing for this to happen.
My guess is this problem was related to cloudflare, because I had no connectivity to all web sites behind cloudflare (including LE) for couple of days. And today it was resolved automatically.
Sorry, I dont have solution, except if it is cloudflare just wait couple of days.
I dont know exact reason why this happened and how it was resolved.
Great! Thanks for reporting back. Another user is having a problem and he too is using Cloudfare. I'm checking things out as we speak. 
Glad to hear it is working but I don't think it is related to Cloudflare (at least for IPv6). @rg305 had you try reaching google and that failed. It is not behind Cloudflare. Just noting for you to keep an eye on. Cheers
We weren't blocking this IP address.
Thanks for the check anyway 