Hi mate good morning. No I am not using any caching plugin. Currently the site is hosted @ Hostgaor.
Strange that I have experienced the same problem on multiple browsers on the same computer. Tried to empty cache and cookies. Still there. Once rebooted the PC the issue disappeared
This is the reply from the technical support:
The error “503 Bad Gateway” in an indication of a caching transparent proxy not properly operating between your location and the server hosting the content. Unfortunately the error is being generated by a intermediate device along the communication path and is outside the scope of our influence. Most likely the Transparent caching proxy is being operated by your ISP or their UpStream Provider.
This in not an indication of a fault in your site. It is an issue of interim communication. You will need to contact our ISP for this issue.
If you have any questions please let us know.