Roon Remote do not connect Roon Core on MacBook Air 2020

Core Machine (Operating system/System info/Roon build number)

MacBook Air 2020(i5 CPU, 16GB), Mac OS:10.15.4
Networking gear model/manufacturer and if on WiFi/Ethernet)

WiFi 5GHz,IPv4(MacBook Air)
WiFi 5GHz,IPv6(ThinkPad T430)

Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)

  1. MacBook Air + iFi micro DSD BL + HeadPhone:Sennheiser HD 600
  2. ThinkPad T430 + iFi nano DSD BL + Marantz HD-AMP1 + DALI
    (Windows10 pro 1903, 16GB)

Description Of Issue

Roon Remote menu on iPhone 8 plus(iOS:13.5)
Disconnect MacBook Air(Roon Core)
and Ready ThinkPad T430(Windows10,Roon Core)

Roon Remote menu on Android Mobile Phone(Ver.9)
disconnect MacBook Air, & Ready ThinkPad T430

Hello @Noboru_Koike,

Welcome to the forum. I’m not quite sure I understand the exact issue here, but it sounds like it could be firewall related. I would check the MacBook Air firewall by using these instructions and if you have any additional firewalls (McAFee/Kaspersky/Bullguard/Little Snitch), I would try temporarily disabling them to see if you are able to connect to the Core.