DIYbanter - View Single Post - Telephone cable

wrote:

I came to grief recently by assuming cat6 is upward compatible with
cat5. IM(very limited)E cat5 & 6 are possibly equivalent at low
frequency, but not at high.

[ tale of woe deleted ]

I'd be hugely surprised if this were repeatable; insulting as it seems,
I think it likeliest you miswired when you used the Cat6; since you say
you did DC tests, the likeliest oopsie was a split pair...

Stefek