Failed to load resource: net::ERR_TIMED_OUT

[thuan7383]

I don’t know where to start to fix this problem.
I still test the site with Lightshouse and sometimes see an error, other times check it without errors. It seems to be unstable.
Failed to load resource: net::ERR_TIMED_OUT
and
TypeError: Failed to fetch at
Can you tell me the cause and fix the problem?
Thank you so much!
My site: HOUSE.com.vn