32km link throughput problem

[CARLOS45]

Hello

I have 2 C5c with 33.5 dbi antennas (ALG-COM PA-5800-32-09-DP) as PTP link.

When I do bandwidth test from the antenna, I get like 100Mbps (first image)

Then when I switch IP traffic over the link, I can’t get more than 20Mbps

Any help/ideas would be appreciated.
Also, I’m thinking on few solutions:

1- Split the link in a chain of 2x16km links to get +400Mbps end-to-end
2- Switch to use a different antenna: ALG-COM UHP-6100-38-18-DP (38dbi, 1.80mts wide)

Here’s some info from AP side

[Nikolay]

this is a ethernet negotiation issue - get both sides of the link to 1000mbps/full duplex.

[CARLOS45]

There’s no problem with eth negotiation.