Maximum speed should be marked on network ports

[lti]

I haven't seen them either, but I have seen fake "Cat6" cables that weren't twisted pair. The ISP-provided cables are at least legitimate Cat5e and have no problem handling gigabit. I wouldn't be surprised if there were Amazon scammers selling cables with only two pairs and four dummy wires (empty plastic tubes to fill the RJ45 connectors for looks) labeled "Cat8" or something else that doesn't exist.

[stj]

most devices other than gaming pc's cant really shift data faster than 100Mb over the card even if it's gigabit so it's not much of a concern.
when i did network testing i used an old SGI computer just so i could use a 64bit network adapter.

the cables are a different matter - i have never seen a cable with only 2 pairs - not even the crap you get free with a router from the isp!

[japlytic]

I noted that a number of consumer entertainment devices have the maximum speed marked on the wired network port and considering that there are broadband plans faster than 100 Mbit, the wired network port can be a bottleneck since some routers do not have Gigabit (only 100 Mbit) support for the WAN port let alone the wired network ports.

One other thing: Certain low cost network cables only have two pairs which limits speed to 100 Mbit.