Hello we encounter the same problem when trying to apply VS 2015 Update 3 on a VS 2015 isolated shell installation.
We retrieved the installation logs with collect.exe and we notice this error which seems to point to broken links:
`[4C9C:5A34][2021-05-07T15:58:31]i338: Acquiring package: Preparation_Uninstall_vsupdate_KB3022398, payload: Preparation_Uninstall_vsupdate_KB3022398, download from: bits://go.microsoft.com/fwlink/?prd=12514&pver=Dev14&sbp=d14rel&plcid=0x409&clcid=0x409&ar=25420.01&sar=S80_RCPrep&o1=B699D32653DB92AEC9BBA467488107ECFA26647E
[4C9C:5A34][2021-05-07T15:58:31]e000: Error 0x80190194: Failed to download BITS job.
[4C9C:5A34][2021-05-07T15:58:31]e000: Error 0x80190194: Failed attempt to download URL: 'bits://go.microsoft.com/fwlink/?prd=12514&pver=Dev14&sbp=d14rel&plcid=0x409&clcid=0x409&ar=25420.01&sar=S80_RCPrep&o1=B699D32653DB92AEC9BBA467488107ECFA26647E' to: 'C:\Users\labusr1\AppData\Local\Temp{7a68448b-9cf2-4049-bd73-5875f1aa7ba2}\Preparation_Uninstall_vsupdate_KB3022398'
[4C9C:5A34][2021-05-07T15:58:31]i000: MUX: Set Result: Return Code=-2145844844 (0x80190194), Error Message=, Result Detail=, Vital=False, Package Action=Download_Bits, Package Id=Preparation_Uninstall_vsupdate_KB3022398
[4C9C:5A34][2021-05-07T15:58:31]w343: Prompt for source of package: Preparation_Uninstall_vsupdate_KB3022398, payload: Preparation_Uninstall_vsupdate_KB3022398, path: C:\Users\labusr1\AppData\Local\Temp\a77efa4c-3094-4a7e-9446-05f4d01d02bc\packages\vsupdate_KB3022398\Preparation.exe
Disabling the antivirus/firewall does not fix the issue.