I am working on an open source library to help with easier integration of GameCenter Authentication and Matchmaking. [REF] https://github.com/SwiftPackageRepository/GameKitUI.swift After successfully getting iOS flawlessly working, I was up to the task to support macOS. So far authentication is working and match making allows me to select players as expected, nearby players are shown so local service discovery seems to work without troubles. But when the inviting from one to another macOS client I always get issues with binding the sockets: 2021-04-03 15:49:31.861398+0200 GKMatchMaker[12213:341178] [authentication] Player authenticated OI234X 2021-04-03 15:49:37.971324+0200 GKMatchMaker[12213:341178] [ViceroyTrace] CDXClient [ERROR] -[CDXClient setError:]:814 (0x7fbb6de35510) err = Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted" UserInfo={NSLocalizedFailureReason=Unable to bind FD to sockaddr. Operation not permitted} 2021-04-03 15:49:37.971427+0200 GKMatchMaker[12213:341178] [ViceroyTrace]  [ERROR] -[GKConnectionInternal CDXClient:error:]:1281 [GKConnection CDXClient:error:]: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted" UserInfo={NSLocalizedFailureReason=Unable to bind FD to sockaddr. Operation not permitted} Any help is gladly appreciated. Thanks.