A mediation server mediating between a terminal device and a communication device may be configured to: receive a permission request from a user terminal, the permission request is for requesting permission for the user terminal to communicate with the communication device via the mediation server; specify the communication information in a memory by using specifying information included in the permission request; send a receipt notification to an administration terminal by using the communication information; in a case where the administration terminal that has received the receipt notification from the mediation server accepts a predetermined operation, store authentication information to the memory; and in a case where the authentication information is stored in the memory in association with the device identification information, send a first storage notification to the user terminal.