I am trying to use my Raspberry Pi as a toy webserver from my home. I do not have a static IP address, so I am using Hurricane Electric's DDNS service. I added an A record for my dynamic public IP, set up port forwarding through my DD-WRT sporting-router, replaced the nameservers on my GoDaddy account with the Hurricane Electric nameservers, etc, etc. Sometimes it works great, but it's not reliable. Occasionally I will get a DNS search failure and sometimes I will get redirected to a search suggestions webpage provided by my ISP. Can anyone help me figure out the missing piece?
Sounds like an issue w/ Hurricane Electric's service, or an issue with your ISP or Pi. One way to narrow it down is: When you can't connect using the fqdn, then try with the IP. If you can't connect using the IP, then either the Pi is choking or your ISP is. you could also put something else behind the same IP to determine if it's your ISP, a file server or another web server or anything really.
Check your public IP address and then try to ping it from external network (3g or 4G LTE) then see if you face same issue because that way you will know whether its ISP issue or issue with DDNS service. You need to test your network for few days then only you will know where problem is as intermittent type of issue needs time for diagnoses.
Your problem happened so recently, it may just be that some old cached information is still being served up by someone in the DNS chain. The linux command "dig your.domain.name" should tell you the name of the server that is giving you the bad data. You can also use "dig +trace your.domain.name" to see the chain of servers that is traversed to find your domain name.