Question about the test network feature in companion

The ardusub page (Redirecting...) says:

if the bandwidth tests achieve greater than 70Mbps, it is a very good connection. Systems with bandwidths below 40Mbps should be diagnosed for issues.

So, I just tested my 200m tether cable combined with the underwater connector for example…

i) QGC is not running behind the “test network”
up: 31Mbps
down: 35Mbps

ii) QGC is running behind the “test network”
up: 42Mbps
down: 41Mbps

It always shows better throughput when QGC is running behind the “test network”.
It is a bit large difference, isn’t it?
Anyone know which one should we choose to decide if it is good connection or not and why?