@Shestakov: I was trying to use Veeam One Monitor in order to connect Veeam One to VBR but the Veeam One Monitor was not loading with the error message cannot connect to service.
@Vitaliy: Both are from the same iso of v8 downloaded from Veeam's website.
I worked on this last night and found the solution and root cause.
1. I had installed Veeam one and Veeam BR and ran the patch for it. i.e. VeeamBackup&Replication_188.8.131.520_Update2b.zip and VeeamONE_184.108.40.2069_Update2.zip
2. Then to get things connected I ran the installer for Veeam One Monitor (BUT I did not run the updater again as the name was a bit misleading as it starts with VeeamONE I thought it wouldn't be required for VeeamOne Monitor)
3. Yesterday when I ran the updater one more time on the server, the Veeam One monitor client started to connect and was fine. To confirm the fix I ran the update2 on my laptop where I had installed the Veeam One Monitor client as well and that started to work too.
Once again, thanks for your prompt response. Maybe a KB article for this issue might help if someone else does this silly mistake as well.
Also any chance for future versions to have a better diagnostics and provide a better error message as to why it cannot connect, eg "Cannot connect to the service as the version of Veeam One Monitor and Veeam One are different".