nsgoyat
Thank you very much for your interests. I said I am using Vultr.com's VPS.
Vultr block several ports from https://www.vultr.com/docs/what-ports-are-blocked. However when i install WordOps last time(around 6 months ago), I succeed all the time. Blocked ports are not main port.
25, 137, 138, 139, 445, 1688, 17, 19, 1900, 53413, 11211
When I install my own ESXi server, It works. I don't know why I couldn't succeed in using Vultr.
Digital Ocean has no problem for WordOps.