Please help: One device (Apple TV) can't see Serviio

I'm at my wit's end and wonder if anyone might be able to help. I've suddenly started having a problem where my Apple TV (using the 8 Player Pro app) is no longer able to see Serviio. I've checked everything I can think of:

1. I've checked other devices. My Android phone, iPhone (also using 8 Player Pro), XBox, and Roku can all see Serviio and play files from it.
2. I've ensured the Apple TV is on the same WiFi network (call it MYNET) as all my other devices
3. I've restarted the Apple TV.
4. I've stopped and restarted the Serviio service.
5. I've removed all known devices from Serviio and seen it repopulate as each of my devices accesses it, but the Apple TV just doesn't find it.
6. I've turned off the firewall on my PC (Bitdefender) and I've also checked to be sure that Serviio has a rule that allows it. It does - the rule allows the Serviio service on all ports, inbound and outbound.
7. I removed the 8 Player Pro app from the Apple TV and then reinstalled it.
8. I've restarted my router (a TP-Link Archer A20).
9. I've upgraded my router's firmware to the latest version.

The Apple TV has no issue connecting to the Internet. I can stream Prime Video and Netflix all day. It simply won't see Serviio, and there's no discernible reason for it that I can find. Anyone have any idea what I might be missing?

So, I finally figured out that this is an issue with the 8 Player Pro app. For whatever reason, that app on that device can't see my DLNA servers. My iPhone, running the same app, can see them. I installed a new app called Player Extreme on the Apple TV, and that app works perfectly. Very strange.

[atc98092]

You could try VLC as well. I have it on my phone and iPad and see Serviio without a problem.