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From the Accelerator clients in the Reports tab shows 'Disconnected from report server'

In a scenario where SSRS (SQL Server Reporting services) is configured to accept only SSL connections additional configuration is required for both SSRS and .NET framework TLS.

In a scenario where SSRS is configured to accept only SSL connections it is required to edit the SecureConnectionLevel section in the RsReportServer.config, additional details can be found in this MS article

1. take a copy of the RsReportServer.config (typically in C:\Program Files\Microsoft SQL Server Reporting Services\SSRS\ReportServer\) 

2. edit the file and save it afterwards

Explanation of the values are:
3: Most secure-Use SSL for absolutely everything.
2: Secure-Use SSL for rendering and methods that pass credentials but don't insist on it for all SOAP calls.
1: Basic Security-Accepts http but rejects any calls that might be involved in the passing of credentials.
0: Least Secure-Don't use SSL at all

3. restart the SSRS server

In addition to the aforementioned it is required to set .NET Framework 4.5.2 to use TLS 1.2 and TLS 1.1 (as mentioned in the MS Article) editing the following registry keys on CA and DA servers:

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

Restart the CA or DA server and proceed with the Reports upload using SSL.