Unfortunately, a Wi-Fi repeater will not offer any improvement. A Wi-Fi repeater would only help improve coverage to an area with weak or no Wi-Fi coverage. It certainly does not improve speed to an area with good Wi-Fi coverage despite what the ads promote. In fact, they actually cut the Wi-Fi bandwidth in half by repeating every piece of data between the Wi-Fi router and the Wi-Fi connected device.
As you are able to get up to 25Mbps offpeak, this also confirms that your Wi-Fi connection is not at fault, but instead with your Internet provider limiting the speed during normal hours.
Both Netflix and YouTube require a minimum of 0.5Mbps to stream in low quality. Many of your speed tests are either under this or dip below 0.5Mbps midpoint during the test, so this explains the buffering issue. I see a few are under 300Kbps, the equivalent speed of a 2G phone data connection. Basically, the Hughes satellite spot beam you're connected to is oversubscribed.
I suggest setting Netflix to download the episodes you plan watching before heading to bed. Basically, pick out everything that you might watch the following day and this way you watch them uninterrupted. A few years ago when I had a slow DSL connection, this was the only way I could reliably watch shows.