iMac unable to Airdrop or connect to LAN

Everything used to be working so smoothly. iMac would connect to local PC and MacBook Pro transferring files by the gigs. Airdrop used to work too. Now it can't be seen by anything. PC & MacBook don't see iMac on the network at all. MacBook sees PC and viceversa. MacBook Airdrops to iPhones & iPads just not the iMac. iMac has just disappeared. iMac connects to internet via WiFi no problem and every other device is using that same WiFi.

I've reset the WiFi network on the iMac with no success by deleting the Network Service and reestablishing it. I've run through the various "reset Airdrop" using various toggle this and that methods but I don't think it's any of the iphone devices since they work with each other and the MacBook. The problem seems to be with the iMac.

Any other advice or suggestion would be appreciated.

Thanks

iMac 27" Late 2013

Mojave 10.14.4