Well, after follow the suggestion of let AGC AUTO on C5, the problem start again and I decided try with jperf to see the max performance over-the-air on the link between A5c-C5:
Jperf - Download -
Jperf - Upload -
So I think the link have enought broadband, i have seen yesterday night 72 Mbps. in both ways, and about 60 Mbps. of TCP traffic both ways too, both with Jperf tool.
But like always the speed test over C5 is not enought good, even if i make some downloads ISO Linux files, drivers, etc
Same files downloaded from the PC on the same switch where A5c is connected are fine.
As always all comments are welcome