M4100 Fiber port not working when connected with another switch fiber port (GS278TPP)

Hi Abelchala,

There can be a few reasons for the fibre connection not working. I have listed 3 common ones below.

1. How far are your switches apart and what type of fibre are you using (multi-mode or single-mode)? Multi-mode is used for short distances and is the "cheaper" form of fibre modules. Typically, the max distance for multi-mode is 500m (but that can vary). Single-mode modules are more expensive, but have much greater greater range. Often 10-20 KMs. You need to make sure that you use Single-mode fibre modules if your switches are far apart and you must make sure that you use the same type of module (single/multi-mode) in each end.

2. Have you checked the fibre polarity? You need to make sure that transmit in one end, goes to receive in the other end - and vice versa. Else it won't work. This is important! Try to swap the transmit with receive, in one end.
Like this: http://community.fs.com/blog/wp-content/uploads/2016/06/polarity.jpg

3. Even though fibre is a standard, sometimes certain modules won't work with certain switches. It is just hardware compatibility. This is why Netgear lists official compatible modules in the datasheet, for each switch. That being said, it often will work with different vendor modules, but not always!

These Netgear modules should work with your switches:
NETGEAR AGM731F (multi-mode)
NETGEAR AGM732F (single-mode)

Cheers