"Fair or reasonable" is irrelevant to whether a non-solicitation agreement is enforceable against you. Also, unlike more general non-competiton agreements or terms, courts have no problems enforcing non-solicitation agreements or terms against employees--you have no intrinsic or inherent right to work with or for your former employer's clients/customers. So if you have signed a non-solicitaton agreement, you will be held to its plain terms and could be sued if you violate them.