Yes, we have found this as well. You can try @Boko suggestion, however we got around this by running sonar and ROV homeplug connections in parallel (so two homeplug boards in the ROV enclosure), sent over a single UTP. You then need a network switch at the surface to connect the topside homeplug board to. We have a BluePrint Oculus 750d and ROV running with no bandwidth issues (max throughput looks to be about 35mbps, well within homeplug specs)…
whoops, I just saw @k-deboer pic, yes, like that.