This is a known problem with these boxes, mine started doing it on 2.2.4 and worse on 2.2.5. Do yourselves a favor, either drop back to 2.2.3 and see how that works out, or like I did, scrap the red box and build a computer, buy a 4 port network card and go from there.
Myself and several others, all in the same boat and we tried everything to no avail. Normally, pulling the network cable out of the port that failed, then plugging it back on solves it, or like you are doing.
I noticed with high traffic it would do it, it just made my systems and network to unreliable to say the least.
Hope this helps.