Hello, @support. Since Roon 1.8, iOS on my iPhone no longer can find my core. I uninstalled and reinstalled the iOS app with the same outcome.
Roon core is working as I have checked on a separate Windows 10 PC with Roon 1.8 on it and I can access and play out through my system.
In addition, neither my Surface Pro2 laptop running Windows 8.1 nor my Android tablet can find the core any longer. Both worked fine before Roon 1.8. I uninstalled and reinstalled on both of those devices with the same outcome as well.
iPhone 7 Plus
Roon app v 1.8.00756
Windows Server 2019 with Audiophile Optimizer
RoonServer v 1.8 build 756
I would also add these exceptions to any Antivirus or other Firewall blocking applications you may have and ensure that you connected to your network via a Private network, not a Public one, see this guide for more information.
If Firewall does not help, can you verify if a fresh Roon install has the same issue?