Duplicate of https://www.sqlservercentral.com/Forums/1901858/Unable-to-access-Reporting-services-reports-from-application. Please stick to one topic per discussion.
As stated in the other topic though, I think you're out of luck. Put your computer(s) in the same Domain or host both SSRS and SQL server on the same server.
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk