Site Admin menu -> Plugins -> Blocks -> Manage blocks
is Network servers hidden?
Still, having any peer displayed in the block requires complete/full setup of a peer. If you don't have admin level access to the other Moodle desired to network, administrator of the other Moodle will have to setup MNet and configure to allow your server access.
Am almost certain I'll be corrected if I say the following incorrectly ... would think twice about relying upon MNet for anything of a major feature/nature. According to previous warning/postings concerning MNet, it was either 'going away' or functionality would be greatly modified.
IMHO, it was one of the features that made Moodle rather unique, but with the coming of things like Web Services and LTI (consumer as well as provider), having something 'proprietary' may not be the best approach to 'future proof' Moodle.
'spirit of sharing', Ken