· My iPhone or iPad as a remote will not connect with Roon core which is in my Grimm MU2.However I can play music through Roon ARC on Apple Car Play in my new 2026 Acura MDX Type S with the Bang and Olufson 31 speaker system. I have done hard resets on my router and the MU2 at the same time and my IPhone 14 or iPad mini A-17 can not find the Roon core. I hope I have given you the information needed to solve this issue but feel free to tell me what else I can provide.Thanks!
Tell us about your home network
· The router make and model is:from Mainstream Fiber and I can’t find the make and model but I don’t use VPN or extenders and I am11’away from the router.
Thank you for the details - the fact that Roon ARC works confirms your Core on the Grimm MU2 is running and reachable from outside, so the issue is specifically with local discovery between your iPhone/iPad and the Core on the same network.
This is typically caused by the router blocking mDNS or multicast traffic, which Roon relies on for local device discovery. ISP-provided routers sometimes do this by default.
A few things to try:
Select a different Roon Server - Tap that button on the waiting screen and see if the MU2 appears in the list. If it does, select it to connect.
Network isolation - Make sure your iPhone/iPad and the MU2 are on the same network segment. If your router separates 2.4 GHz and 5 GHz into different subnets, or has any “AP isolation” or “client isolation” feature enabled, devices won’t see each other. Check your router’s wireless settings for anything like that.
Router mDNS/multicast settings - Since it’s an ISP-provided router, you may want to contact Mainstream Fiber to ask if mDNS or multicast is enabled, or if there’s a way to disable AP isolation.
Since the Grimm MU2 is the Core device, I’d also recommend reaching out to Grimm Audio support - they may have specific guidance for networking their device on your setup.
Could you let us know what you see when you tap “Select a different Roon Server”?
Just checking in on this. Have you had a chance to try the “Select a different Roon Server” option and see whether the Grimm MU2 shows up, and did you get anywhere checking for network isolation or mDNS and multicast blocking on the router? If it helps, we also recommend taking a look at our Networking Best Practices notes while you test those settings. Let us know what you find, thanks.
