I have two HaloLink1 units. One is configured as AP and the other as EXT. Both are linked and when close to each other can obtain a link speed of 28 Mbps. If I move them apart by approximately 300 yards, that have less than 0.4 Mbps. It is literally clear line of sight between the two over a small pond. The YTube video shows much further range with clear line of sight.
This is in a small residential area with only a dozen houses within 100 yards of each device.
Any thoughts as to why the range is so poor for me?
Given that your description of the environment sounds like it should be very clean from an RF point of view, I would be interested in knowing the noise as measured by both the AP and extender devices, as well as the RSSI and MCS index.
If you can, please share a screenshot of the associated stations list in the Advanced Config → Wireless tab, as this will have all of that information. Please capture this information while traffic is flowing to ensure the highest MCS rate for the link is used.