Looking for logging into the Salesforce Sandbox site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Salesforce Sandbox site. After that you can login as usual with your login credentials.
https://login.salesforce.com/?locale=de
https://developer.salesforce.com/forums/?id=906F00000008kVjIAI
https://success.salesforce.com/answers?id=90630000000h1A1AAI
https://help.salesforce.com/apex/HTViewHelpDoc?id=data_sandbox_create.htm&language=de
https://help.salesforce.com/htviewsolution?id=000175987
https://success.salesforce.com/ideaView?id=0873A000000CPZyQAO
https://help.salesforce.com/apex/HTViewHelpDoc?id=data_sandbox_create.htm&language=en
https://salesforce.stackexchange.com/questions/31543/how-to-login-into-a-sandbox-from-sandboxes-page-in-production-org
https://help.heroku.com/IAYGFF7A/why-can-t-i-login-to-my-salesforce-sandbox-org
https://www.youtube.com/watch?v=_jTlTDKYdAo
https://www.tutorialkart.com/salesforce/salesforce-sandbox-login-test-salesforce-com/
https://github.com/forcedotcom/sfdx-simple/issues/29
https://workbench.developerforce.com/