U231F access point - aggregated bandwidth of 2 gigabits

[matteocostanzo]

I connected a FortiGate 100F to a FortiSwitch 248E-FPOE using four cables to set up a 4-gigabit trunk.

Then, I connected a U231F access point to ports 3 and 4 of this switch, with the network interfaces configured in uplink and LACP enabled to achieve an aggregated bandwidth of 2 gigabits.

I also connected two desktop PCs to ports 29 and 30 on the switch, each with a Gigabit connection. On both PCs, I placed a 3-gigabyte file.

If I start downloading the files simultaneously from two notebooks connected via Wi-Fi to the radio on the 5 GHz band, one of the PCs downloads at 300 Mbps, while the other downloads at nearly zero speed. Once the first download finishes, the second begins. I would expect both notebooks to download the file at the same speed of 300 Mbps.

[ebilcari]

Is the SSID in bridge or tunnel mode, and is the file hosted on the same server?

Keep in mind that while LACP provides aggregated bandwidth, it uses an algorithm (based on IP/MAC) to distribute the load across links. However, it won't utilize all links simultaneously for the same calculated session.

[matteocostanzo]

the SSID is in bridge mode and the files is hosted in two pc desktop. notebook 1 download from desktop 1 and notebook 2 download from desktop 2. 

300 Mbps is really low compared to the theoretical 1.2 Gbps, leaving aside LACP for the moment.

[ebilcari]

Than this seems like a WiFi protocol limitation, most probably the connected hosts on that SSID don't support the latest protocols and are working in 802.11n.