Dandelion access terminal cannot log in, prompting "Connection to server failed". When it can't be used, you can try the following actions: (1) Change the computer DNS to efficient DNS such as 223.5.5.5 and 1 19.29.29. (2)ping dandelion's API server domain name. (3)Telnet Dandelion API server port 443. (4) The agent network cannot use dandelion software.