Dear Friend!
Was impossible for me to attach the grcpool to the BOINC in the instance of the Google Cloud.I think that I know why, it is because there is a problem with my password which uses a symbol that creates a conflict with the boinccmd :-)
Took ages to discover that... at the end, the only way to solve it was, either by changing the password which would create problems with the other computers I have attached or by creating an instance for windows server. The second works perfect so now I have another 8 core machine with boinc and fully working with grcpool.
Thanks for your attention and help!!
keep on crunching!!!