Thank you for your info, we will consider to test it, if we find this motherboard in our country.
I checked your offer, you made excellent hardware combinations! But, unfortunatelly we cannot use v3 for this particular purpose. If we can, our problem will be solved immediatelly, we can just wait new versions of routerOS to fix problem or use v2.9.X where problem doesn't exist with as much powerfull hardware as we can. But our choice is limited.
So far, Pentium D with motherboard which supports v2.9.X will be the best choice available. Or some combination with XEON processors. But I am not sure which combination fo Xeon processors works on v2.9.X. Letni, mention one.