The physical media is always a suitable place to start troubleshooting on. Cables are often exposed to tensions or nature. In the air which is the media for wireless radio or light signals there is a risk for interference of different sort. A shortcut is to step up to the link layer and check if the physics are OK.

Cupper

Make a check of your cable to se if it is connected or damaged anywhere. If you can't see anything you need an instrument to measure the cable. Those are available at most shops selling instruments. The most common cable used today is category 5, a pair twinned cable with four pairs, for new installations category 6 is used today.

The connections use to be of a type called RJ45 with eight contacts that is straight connected between both ends. For 10 and 100 Mbits only 2 pairs is used but for Gbit all 4 pairs is used. The straight Ethernet cable is used to connect between switches and end equipment like PC:s printers etc. For connections between the same type of equipments (switch to switch or PC to PC) a special crossover connected cable is used.

Fiber

When it comes to fiber cables they are much more sensitive than cupper and should be handled with care. It is not permitted to bend the cables in too sharp angles. You can actually see the light in the fiber if you look straight into the fiber end. As there are a send and a receiving fiber you only see light in one of them. There are two types of fibers commonly used, so called multimode fiber with LED lamps for short distance and single mode fiber with laser lamps for long distance (between buildings). Laser is far more expensive.

Beware of eye damages if you look in to laser lamps.

Wireless

Wireless becomes a little bit more complex as you can't see the radio signals. However it is mostly easy to know if you are within the risk zone. Dependent on the quality of sender and receiver you shall reach 10-20 meters indoors but much longer distances outdoors. With no obstruction of the signals you should be able to reach a couple of hundred meters.

Walls of solid material as concrete, stone or steel is always more difficult to get through with radio signals than plaster or tree walls. There are simple applications where you can listen to wireless LAN radio signals, one of those you will find on our free programs page on the download pages.

When you are ensured of that the physical media forwards the signal you can take a step up in our OSI model to the next layer that is the link layer (Ethernet protocol).

Continue troubleshooting here