Looking for logging into the Rz10 System_client 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 Rz10 System_client site. After that you can login as usual with your login credentials.
https://wiki.scn.sap.com/wiki/display/Basis/How+To+Change+Default+Logon+Client
https://archive.sap.com/discussions/thread/1062137
https://blogs.sap.com/2014/11/13/how-to-change-the-default-logon-client-on-sapgui-logon-screen/
https://help.sap.com/doc/saphelp_nwpi71/7.1/en-US/22/41c43ac23cef2fe10000000a114084/content.htm
https://rz10.de/sap-basis/profilparameter-zur-umsetzung-von-kennwortrichtlinien-in-sap-systemen/
https://rz10.de/sap-basis/sap-stern-freischalten-in-netweaver/
https://rz10.de/sap-grc/uberprufung-der-sap-standardbenutzer-auf-initialkennwort/
https://www.dv-treff-community.de/sap-hilfe/Standard-Mandant-t913
https://it.toolbox.com/question/how-to-set-default-login-client-092006
https://www.sapebooks.com/blog/change-default-client-in-sap-logon/
https://www.youtube.com/watch?v=7GuSIDwQosU
https://itsiti.com/define-default-sap-client-login
https://www.abapforum.com/forum/viewtopic.php?t=2496&p=10593