Looking for logging into the Plesk Onyx User For Sub Domain And Panel 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 Plesk Onyx User For Sub Domain And Panel site. After that you can login as usual with your login credentials.
https://docs.plesk.com/de-DE/12.5/customer-guide/websites-und-domains/domains-und-dns/hinzuf%25C3%25BCgen-von-subdomains.65180/
https://support.plesk.com/hc/en-us/articles/115000381434-Can-t-login-to-Plesk-Panel-with-system-user-credentials
https://support.plesk.com/hc/en-us/articles/115000205953-How-to-create-a-user-for-managing-existing-domain-in-Plesk-UI-
https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/6216391-login-panel-from-subdomain-and-not-port
https://mediatemple.net/community/products/dv/204644820/creating-additional-plesk-control-panel-users
https://mediatemple.net/community/products/dv/204643700/creating-a-subdomain-in-plesk
https://www.netcup-wiki.de/wiki/Plesk_Onyx_Panel_Webhosting
https://help.fasthosts.co.uk/app/answers/detail/a_id/1990/~/understanding-the-different-user-accounts-available-within-plesk-12-%2526-onyx
https://www.liquidweb.com/kb/how-to-add-users-and-assign-roles-in-plesk/
https://codex.wordpress.org/Configuring_Wildcard_Subdomains_for_multi_site_under_Plesk_Control_Panel
https://www.conetix.com.au/support/article/how-add-subdomain-plesk-onyx
https://manage.accuwebhosting.com/knowledgebase/2369/How-to-delete-Domains-and-subdomain-in-the-Plesk-panel.html
https://www.hosteurope.de/blog/wordpress-installation-ueber-plesk/