I have a 25 meter Cat5e ethernet cable connected to a FritzBox and a computer.
If I'm using a short cable I will get an 100 and 1000 Mbps connection respectively.
But with the 25 meter cable I will not get any IP of the router.
Otherwise if I set
ethtool -s p4p1 speed 10 duplex full autoneg off it works.
Obsolete: Is there any reason for that? I pretty sure cable length of ethernet is not limited to 25 meters but 100 meters.
I could also live with 10 Mbps. But I don't want to fix that so if there are other communication partners and shorter wires respectively I don't want to limit that speed too. So the easiest way if the configuration is correct, to have a "fallback" routine not only to stay connectionless but also use 10 Mbps as a fallback. I'm not familiar with the negotiation process.
I wonder about setting 10 Mbps manually will work but the devices don't get it themselves. Maybe the negotation just avoids to attend an unstable connection?
The ethernet cable is in a UV protected tube within the power supply. However it doesn't work with unplugged power supply too. And it cannot be easily replaced due to time and cost reasons.
I noticed that the cable is split up and soldered again so that it can be plugged. I think thats the weakest link. So testing the cable would be the best way to go. Btw. what output do I expect of an cable tester? The frequency to which it will work correctly?
Finally How can I get 100 Mbps and 1 Gbps connections and if that is not possible force 10BaseT? Right now the negotiation process just hangs. Or how can I see clearly why it hangs?