No connectivity to Micro Rendu device

I have new iMac with a cable moden connecting via ethernet cable to the MR to my Aqua LaVoce DAC.  I use Audirvana and it sees the MR but does not see the DAC.     I have spent hours and hours DXing the problem and have failed.  Neither Sonicorbiter nor Audirvana have been of any assistance.   The MR is a vital addition to my system -- when it functions, which is very rare.  Can anybody help me out? Thanks.