Q: Since a few days my w-lan connection is extremely slow, while the Router seems to work perfectly. At the same time I seem not to be able to update with time machine on my Time Capsule

Grant, why are you replying to me? I am not having network problems. LS26870-LAS_5GHz is my network

so sorry. I got completely confused and picked the wrong one. I will try again.

My apologies for my previous mistake in posting an analysis of lllaass network instead of yours.

on your connection to JuliaD:

you are using 802.11n mode on channel 52 in the 5GHz band. Your 40MHz signal will spread up and down the spectrum, and parts will be interfered with by other Routers using nearby channels.

Your signal strength of -67 less the noise level of -90 gives signal-to-noise of only -23, which is good.

Your transmit rate of 270 is twice the baseband speed of 135. 135 is the fastest baseband speed possible using 802.11n and 40MHz. You are sending your signal using two antennas, and your actual signal is the difference between the two antennas' signals.

Even with so many neighbors, You should not be having connection issues. There are a few things you can check:

Be sure IPv6 is set to link-local only.

Be sure you have turned OFF "wake for network access" in energy saver unless you intend to actually use it.

Create a new Network Location as lllaass suggested.

If you continue to have problems, you can use an inexpensive Utility called WiFiExplorer to create a frequency-spread diagram of the networks in your area. Its diagrams look like this one:

(click to enlarge)

this diagram show just how far up and down the spectrum each nominal channel spreads. It helps you understand that, for example, someone using nominal channel 36 can cause interference as far away as channel 50.