Error 521 Server is down when search

When i use search, it shows error 521 server is down. Please help me to check what error is? Thank you!
For example:
https://beattienao.com/?s=Blockchain+la+gi is working fine.

But when i access my home page and use search with keyword “blockchain la gi”. I show 521 error.

• This topic was modified 5 years by beattienao.

Hello team,

I have not yet fixed this issue. When i use the search botton on the home page, type some keywords, press Enter, Webserver is down then. Sometimes, it shows Database error.

If i search via the search page (https://beattienao.com/?s=), it works fine.

Anyone can help me?