CM500 slow connection

> [...] getting about 90Mbps from all computers. I tried directly
> connecting to the CM500 and still get 90. [...]

   Ask the OS on one of your "all computers" about the speed of its
Ethernet interface.  It should be able to negotiate a 1Gb/s rate with
the Ethernet interface of the CM500, but if all it gets is 100Mb/s, then
you could have a damaged connector, or (partially) fried port, or bad
cable.  All eight conductors are needed for 1Gb/s; only (the right) four
for less.

"directly connecting" what?

> [...] I have never gotten much more than 200Mbps on my older MacBook
> Air hardwired through an Apple Airport Extreme. [...]

   200Mb/s is more than 100Mb/s, so that couldn't be cable- or
interface-limited.

> [...] changing the ethernet cables. No luck. Always stays at 90Mbps.
> [...]

   Look at the LEDs and the reports from the software.  Identify the
bottleneck.

> Cable Model CM500 status 210213.pdf

   My cable-TV-modem expertise is nil, but I'd expect 16 happy channels
to do better than 100Mb/s.