The wire gauge is slightly larger for Cat6 (23 gauge) but that was done to provide the needed headroom for the overall performance. You should have no problem going 30 meters, however, here is what I have seen that makes the cables NOT work:
1. Most common error - improper termination, mainly a split pair. Sorry to harp on this one, but it is the most common problem I've seen. Pins 1 and 2 MUST be use a twisted pair, and pins 3 and 6 MUST use a pair. If you don't have it wired this way, this is quite likely your problem.
2. Too much untwist when terminating. If you are putting jacks on the end, be sure the minimum untwist of 1/2" is observed. If you are putting modular plugs on the end, it is even harder. In the early networking days, 10 mbs was pretty forgiving. However, to make it fly at 100 mbs or higher you really have to play by the rules. Be sure you maintain the twist as close to the termination point as possible.
3. Bad hardware - be sure the modular plugs you are using are designed for the type of wire (if you are terminating on plugs). There are plugs for solid wire, plugs for stranded wire, plugs for flat wire, plugs for round wire, and plugs that do solid AND stranded, etc. The wrong plug can give you DC continuity but still not provide solid connectivity.
4. Wire - I've seen stranded wire used in the field for cabling with poor success. Keep in mind that stranded wire has much greater attenuation per foot, the wire is used only for patch cables, which are limited by standards to relatively short lengths (I think the longest allowed is around 70 feet, but I'd have to look that up).
SO, if you are terminating with the correct pairs, using solid wire, using the correct good quality jacks or plugs and keeping the twist to a minimum, AND still it doesnt work, I suspect you have a NIC or hub problem.
Hope this helps, please keep us up to date with what you find for a solution, I'm always curious what finally worked for people.
Good Luck It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com