一个工作网站突然开始拒绝连接

I know this question is probaly repationg question. But all the other questions had a different solution that did not work for me. Here is the screeshot of my error

I tried to change DB_HOST=localhost into DB_HOST=127.0.0.1 but it did not work, and I also tried to change url into https it seem to make no difference. Any help is appreciated in advance.