The LAN connection from a computer to my home-network stopped working from one day of the other. First I thought, it could have to do with the network-lan-card in the specific computer. Sadly I did no detailed test and did not locate the problem exactly.
Weeks later I realized, that other computers in the network couldn’t connect too over LAN. Next I updated the router (FritzBox 7390 ) to the newest firmware version (6.25). This didn’t solved the problem. If a Computer was directly over LAN connected to the FritzBox, everything worked. So the only bad thing between could be the Netgear 8 Port Switch GS608 v2. Strange was, that the LEDs in the Switch light up, if a device was connected by cable.
Because the switch is capable of 1Gbit/s it has two LEDs per Port (green an orange). If a 100Mbit/s device is connected, the orange LED shines. If a faster, 1Gbit/s device is connected, the green LED shines.
I recognized, that the FritzBox (capable of 1Gbit/s) was detected by the switch as 100Mbit/s = slow = orange light. My Laptop could only connect every 10 seconds for about one second. Really strange.
If I connected a 100Mbit/s Switch between my Laptop and the faulty Netgear Switch my connection to the network worked!
It turned out, that 100Mbit/s connections through the Netgear Switch worked, but faster connections caused problems.
Also only a number of devices were working properly, if more than 4 devices were plugged in, the later added devices couldn’t establish a connection – the LEDs of their ports stayed dark.
I didn’t know, what was happen with the router, which worked fine for 7 years. I searched the web and found randomly a post about a fix for this router https://tinajalabs.wordpress.com/2011/03/20/netgear-gs605-v2-fix/. The writer recognized, that his internet-connection was slow and searched the web and found, that bad capacitors in the switch can cause the problem.
I opened up the switch (4-Torx screws on the bottom under anti-slip pads) and saw the two blew up electrolyte capacitors. A third electrolyte capacitor was fine.
I unsoldered the capacitors and replaced them by two with identical capacity (1000uF) and voltage (10V) rating. (Mine are only rated 85°C and not 105°C like the old ones, but I think, they should last at least some years).
Problem solved, everything works again at full speed, as it should. I think this is a product more with planned obsolescence. Two small parts can make the whole device waste. And not everyone knows who two change electrolyte-capacitors.