It looks for me what someone bully me with not sufficient "guitar" posts, since we know now that problem is not guitar
I'll try one last time to get this thread back on track, and on topic.
001, there may indeed be nothing wrong with the guitars you tried. (I.e. in a more typical environment, they may work just fine.) But in the challenging environment next to the server room, improving the shielding on the guitars and amplifier, and maybe selecting a particular type of pickup for the guitars, my be the only realistic solution to the interference problem. More likely than not, you can't change things at the source (assuming the signal comes from the servers).
So, unless your friend wants to find a different room for practice, the questions others have asked about the guitar(s) and their shielding are valid. -- On the plus side, the servers will probably not mind your friend's acoustic noise much; so this practice room has its merits.

Why don't you get back to troubleshooting, and restore the thread's title to something more meaningful?