cant not login panel after restart

after i restart my server I Got Error 522 my web going down can anyone suggest me what happened

NOLe
Did you use CloudFlare to proxy the panel address? If yes, please cancel the proxy

just use ur login panel

aaPanel_Jose no I dont use cloudflare for my panel

and now my few visitor got error 521, I still dont know whats the problem is

NOLe
I'm sorry you provided too little information, I can't help you

Please provide the website access log and error log, as well as the screenshot of the access error for me to see