1- When connected to my local network, one unit shows a bandwidth of 7,500kps to 8,500kps. The other unit which is on the same network shows a bandwidth of 3,500k to 4,500k. Why the difference if I have forwarded the port for each unit?
Well, that depends. If you're trying to run *both* on the network at the same time and you're trying to push over wireless; it's possible you're just maxing out the available amount of bandwidth you can push through the air. If this isn't the case and one is about half the bitrate of the other; I'd make sure they're both connected to component video and the box is outputting 1080i. If one is hooked up to composite and/or not getting a 1080i or 720p signal from the cable box; that would account for the drop in bandwidth. If they're both getting HD signals and the bandwidth is still off; you might have a bigger problem. Forwarding ports doesn't help on the local network; that only helps you connect from the outside.
2- I have family trying to watch these units in Australia. The maximum bandwidth they are able to receive there from my unit is 2,200kps. Is it possible to get this higher so they can get to the 3,000kps mark and view in BEST HD? While logged onto other external networks or the LTE ATT network on my phone I could get up to 4,200k signal. Would it be normal to lose 2,000kps from Los Angeles to Sydney? Any way to speed it up on their end?
If this isn't because your relatives have slow internet; it's quite possible it's just a limitation of how much data you can push across the ocean. Bandwidth capacity for the undersea cables isn't anywhere near to what we have moving around the US; so losing 2mbps may be perfectly normal depending on the carriers involved. They may be able to connect to a VPN service that terminates in the US and gets better signal; if that somehow routes thier connection a different way. But I'd be willing to bet it's largely just a limited amount of bandwidth involved crossing the ocean.