dmctl -s <domain> findInstances Interface::IF-myRouter*
To resolve this issue specify .* (with a "period" preceding the asterisk) instead of just * as in the following:
dmctl -s <domain> findInstances Interface::IF-myRouter.*
It is also good practice to put the expression in quotes as in the following:
dmctl -s <domain> findInstances Interface::"IF-myRouter".*