1.5gbps WAN poor performance on LAN

[Sasquatch5177]

Hi guys so let me explain what is going on, its not a huge problem for me but i'd like to get it fixed.

I'm with Bell FTTH in Canada I connect with PPPoE and they give me 1.5gbps, I bypassed their router with mine, with a 57810S NIC card 2x SFP+ interfaces.

When I try a WAN speedtest with the command "iperf3 -c bhs.proof.ovh.ca -u -b 2g -R" on opnsense it gives me 1.64gbps which is exactly what i'm supposed to have. The problem is when I try the same command on my server on my LAN or my computer I cannot get above 1.34gbps.

The server and computer are connected at 2.5gbps on a 10gbps capable switch. When I do iperf between my PC and my server I get 2.35gbps so I saturate 2.35gbps. Also, when I try the same iperf with opnsense being the host for iperf I get the same speed 2.35gbps.

Honestly i'm not a pro so I didn't try a lot of things, I played with MTU but it didn't change anything, any ideas?

Thanks.

[mimugmail]

What happens when you flip direction? How much upload do you get?

[Sasquatch5177]

It's a 1500/940 package and I have no problem maxing the upload at around 950/960 mbps

[_nwb]

Force IPv6 with TCP only and UDP only, and then IPv4 with TCP only and UDP only. Could also use the -b flag to give it a target throughput.

I'm having issues with TCP IPv4 upload throughput only, and I cannot make it make sense.

[Sasquatch5177]

Unfortunately Bell doesn't offer IPv6...

[Sasquatch5177]

Just a quick heads-up, it's a bit weird but doing speedtest over speedtest I can see that I can sometimes get the full bandwidth, its like 50% of the time 1.2gbps and the rest 1.5/1.6. When I can get 1.6 it is very slow to go to 1.6 tough.
Here's a screenshot of a speedtest history.