IDEA连接数据库出问题：Connection to @localhost failed.[08001] Could not create connection to database server

Host key verification failed. lost connection解决方法

Call from hostname/127.0.1.1 to localhost:9000 failed on connection exception.

Springboot配置Websocket，前端提示WebSocket connection to ws://localhost:8080/* failed

CODING 提示: Authentication failed.

warning: Clone succeeded, but checkout failed.

阿里云服务器实战-阿里云 Could not connect to '' (port 22): Connection failed.

Some Enforcer rules have failed. Look above for specific messages explaining why the rule failed.

cannot connect to host localhost:7210 [Connection

浏览器插件下载“Download failed. Please check your connection.”解决方法