Serviio networking issue

I have the problem that when I connect my Home Server PC running WHS 2011 with Serviio 1.1 to the router / modem directly, the other wired (and only wired) devices (Samsung TV and PS3) on my network do not detect Serviio and the other way around. This does not apply to any wireless devices (laptop, tablet, smartphones and PS3 to wireless mode), all these devices see the Serviio server just fine.

If I connect the Server to a switch (the same switch where the Samsung TV and PS3 are also connected - switch is connected to the router / modem) then the Samsung TV and PS3 can see the Serviio server.

- Serviio server has a static IP 192.168.1.100 and is also bound
- PS3 and Samsung TV also have a static IP 192.168.1.101 and 192.168.1.102
- TCP port 8895 and UDP 1900 are open for both outgoind and incomming connections on the Serviio server
- the router / modem is a wireless Huawei HG655b with UPnP enabled
- PS3 and Samsung TV can connect to the internet just fine
- I can ping the IPs of the wired device (192.168.1.101 and 192.168.1.102) from the Server
- Serviio server does not detect the IP / devices in the Renderer Profile box at all, the devices also do not detect the Serviio server unless I connect the Serviio Server to the switch where the wired devices (Samsung TV and PS3) are also connected, then it the devices are detected and everything works really well.

I am attaching the Serviio debug log.

Would really appreciate any suggestion of the more network skilled. Thank you very much.