Symptoms

K2 has been configured with two K2 app servers in NLB cluster. In client event notification, link for the task is generated using filed "Worklist Item Link". For some reason this field is being resolved into direct link towards one of the servers in cluster and not into NLB name.
 

Diagnoses

Please go to Workspace - Environment Fields and double check that the SmartForms Runtime Field set to be Default is pointing to the correct NLB URL. Next, the Items you are opening.

Are these Default Clients Events or SmartForm Client Events? If Default Client Events, please review the Event's configuration and check which Value you are using to build up the Task URL.

Make sure that this Environment Field/Process Datafield is pointing to the correct URL. If SmartForms Client Event, then updating the Default Runtime URL should fix this.

Note that only new Items will show the updated URL, existing Items will not be affected.
 

Resolution 

Cause of this issue for SmartForm Client Events is incorrect value in SmartForms Runtime Field which may contain specific server name instead of NLB cluster name.

Adjusting SmartForms Runtime Field should resolve this problem. See also additional details above.