constant internet drop outs - help!

hi all!

i am having issues with internet drop outs every now that is slowly driving me crazy. the intervall between these drop outs can be anything between 30 minutes to a couple of hours and they don't last for more than 30 seconds.

the setup i have looks like this:

broadband socket > virgin media superhub > homeplug > asus router (rt-n10e)

the virgin media superhub is connected to the broadband socket in my room downstairs. i have connected a homeplug device to it which transports the broadband via electricy lines to my homeplug device in the room upstairs. i have then connected the asus router to my homeplug upstairs. the reason for this setup is becaue i am using a smartDNS service which means i need static dns in order to view some programs via my chromecast device. the virgin media superhub won't allow me to change the dns, that is why i am using the asus router to do that job for me.

now, everything is working perfectly fine (the speeds are great) until the actual drop out. this makes the tv screen freeze (if i am watching a tv show via chromecast) and i am not able to browse the internet on my computer. this lasts for like 30 seconds until i can start using the internet again. i don't need to reboot anything to make it work again.

i have been trying to figure out why this is happening but i can't come to a solution.

would anyone be able to help me in this matter?

huge thanks in advance!