Issue With Ethernet Interface

hello , i have issue with interface mimosa b5c , the link work fine but the cable network read 10mb /half duplex , i tried chang the cable with other cable but the same problem , the same cable tested with c5c read 1Gbps Full deplux , i tried change the power adapter the same problem , i tried connect the cable direct in the b5c the same issue.
Note
Installed Version 1.5.1.
the total length of cable about 20m.
i try connect with Mikrotik 4011.
in the same tower there c5c read 1Gpbs

Could be you have a dead port.

What are you using for the cable?

Are you nearby other large transmitters like an FM tower?

i don’t think that because when i connect for short distance it’s working

the tower of FM away from my tower about 7KM

Ya, that’s probably not a significant issue then.

Do you mean when you say “connect for short distance it’s working” that when you use a short cable to connect to the B5c you don’t have an issue, it’s just over the longer cable that the issue happens?

yep short distance about 10 m i have issue when the cable length over 11m

What kind of cabling are you using? The difference of 1m and then there is an issue seems unusual on its own.

Maybe already done, but tested with a different cable at the greater than 11m length?

The detail of exactly what you’re using for a cable could be important, but CAT5e should be more than fine if the only difference is 1m. I only use CAT6 cabling, but really, based on the information here, I would be wondering about the cable itself unless you’ve tested with a different one and have the same results.

Normally I would say there might be an issue with the cable, but that is super weird if you have already tried changing out the cable. You also have mentioned that you plugged the cable into a C5x and that radio didn’t have the issue.

Could there be some sort of electrical noise in the area?

What kind of grounding do you have?

Is your cable shielded?

The C5x negotiating at the higher speed could be a sign of either an issue with just the B5c or that the C5x’s grounding is better or that the C5x isn’t responding to the noise, or bad cable, as quickly as the B5c.