If your daugher's room is in the same electric meter as well, I think TL-WPA281 is a good choice in your situation. You can pair your existed PLC device and WPA281. And then, when you plug WPA281 in...

Try to DMZ and see what happens.

In WAN preferred mode, ethernet is working as WAN port for you to plugin a DSL modem or cable modem, not LAN port. It is LAN port when in 3G only mode.

You may try driver for Windows Vista.

after while I am connected to BR0 and I am able to ping IP from VLAN55 for a few seconds then router restarts, boot, work for few seconds and restart again, and so on ..... WA901ND will restart...

Other players may not be able to discover the media server due to that they don´t support DLNA protocol.