network not appearing in finder sidebar

I have an Imac and a Macbook Pro running Catalina. At first I could share files easily over my wifi network but lately I was unable to access the Imac from the Macbook. I could still access the Macbook from the Imac. Today I have no network icon and no shared computers in my finder sidebar and I can access either computer from the other even using the computer address. I have sharing turned on on both computers and I have selected to show connected servers and bonjour computers in the sidebar. I tried restarting the computers. I have not restarted my router. Is that the next step? Thanks.