MacBook loses access to Home Assistant (Connection refused on 8123) after about a day, while iPhone and Apple Watch keep working

Installation
1

[URGENT]
Hi all, I’m running Home Assistant OS 2026.9.4 on a Raspberry Pi 5 (IP 192.168.1.105). My iPhone Companion app and Apple Watch connect and control devices without any issues, but my MacBook loses access to Home Assistant.

This keeps recurring: after a reboot of the Pi, the Mac connects fine for about a day, then starts getting “Connection refused”. The iPhone and Apple Watch keep working throughout.

What I’ve tested from the Mac while it’s failing:

  • ping 192.168.1.105 works with 0% packet loss
  • arp -a shows a Raspberry Pi MAC address (88:a2:9e:…) for that IP
  • curl -I http://192.168.1.105:8123 fails with “Couldn’t connect to server”
  • nc -vz 192.168.1.105 8123 gives “Connection refused”
  • homeassistant.local:8123 is also refused

Other details:

  • The Mac and phone are on the same Wi-Fi
  • The browser (Arc) has Local Network permission in macOS
  • The macOS firewall was off during testing, and no VPN is configured
  • I recently uninstalled Tailscale from the Mac

Has anyone seen Home Assistant start refusing connections from one device after a day while other devices keep working? Any ideas what to check next?

2

Try on default port 80, using no port at all…