The rule to enable/disable nodes of a multinode environment is: 'nxserver --ruleadd --class feature --type enable-multiserver --value yes' which may be misleading.

Option 'enable-multiserver' should be instead 'enable-multinode'.

Note that when the rule is set to no, it applies to all nodes. I.e. 'nxserver --ruleadd --class feature --type enable-multiserver --value no', forbid all users to connect to all nodes.
Additionally, the 'enable-multiserver' rule is not listed in the output of 'nxserver --resourcelist' while it's listed in output of 'nxserver --rulelist'.