This question is an exact duplicate of:
For about a week now, I have been unable to access any Stack Exchange sites from my home network. Whenever I try, the browser tries to load for a while, then says it cannot connect. The only way I have been able to access the sites is via a proxy.
All packets are lost when I ping the server:
>ping stackoverflow.com Pinging stackoverflow.com [220.127.116.11] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 18.104.22.168: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
I believe this is perhaps something to do with the recent change of the data centre. I first thought that this was a DNS issue, but it has been a week now (and I assume you have proxies in your old data centre). The only alternative I can think of is that my IP address is, for some reason, blacklisted.
Is this a known issue? Is there a solution?