When Microsoft made changes to networking and removed Homegroup from Windows 1803 and that caused some problems.
To get you PC's to visible under File Explorer network section then most important part is to start some required services, but you have to check all network settings.
Push Win Key and type "Services", locate those services, start them and set Start type to Automatic.
Services are:
- Function Discovery Provider Host
- Function Discovery Resource Publication
- SSDP Discovery
- UPnP Device Host
Look more detail from my example with screenshots how to make PC's to show in File Explorer network section, change network profile and setup file/folder shares.