Serviio 2.3 can't be seen in any of the devices

So I upgraded the Serviio to 2.3 on my old Qnap TS469L. It's running cuz I'm able to see it via the web GUI. However, none of my other devices are able to see it (DLNA). I have JRE 8.151.2. Anyone else has this issue in the past and has a solution to it? Please advise?

I found out why but it still makes no sense. I move the network cable for the QNAP outside of the switches and plug it back into the hub and that seems to solve the problem. Very strange. Is there a protocol in Switch that I need to turn on for the devices to see the Serviio? I'm using Cisco SG300-20 for my Switch. I'm curious.

[atc98092]

Since you're using a Cisco managed switch, it's entirely possible there's some setting within the switch causing the issue. It's been more than 10 years since I've messed with managed switches (and they weren't Cisco), so I really can't point to any specific setting. If there is something blocking Multicasting, that would be one possible area to check.

I'm seeing a lot of people mentioning something about multicast and I'm guessing I didn't turn on the multicast on my switch. I haven't gotten a chance to test it yet but I'll keep everyone updated when I have the chance. Thanks for the pointer though.

[atc98092]

uPNP uses Multicast to advertise itself on the network, so if your switch is blocking uPNP (UDP port 1900) that would make it impossible for devices to see Serviio.