I have a 10Gbps internet connection. On a system with a 10Gbps Ethernet card, I can get ~8Gbps down and ~6Gbps up:
I'd expect this to easily max out a 2.5Gbps network connection. However, while the upload is maxed (or close to it), I can only ever get ~1.0 to 1.5Gbps down:
Both tests were performed on the same system. The only difference is that the first one uses a TRENDnet 10Gbps PCIe network card (which uses an Aquantia AQC107 chipset) whereas the second one uses the onboard NIC on my motherboard (Intel I225-V chipset).
This is consistent across two devices that have 10Gbps ports and two devices that have 2.5Gbps ports.
I'm using an AdTran 622v ONT provided by my internet provider, a TP-Link ER8411 router, and a MikroTik CRS312-4C+8XG-RM switch. I'm using CAT6 cabling, except for the connection between the router and the switch which uses an SFP+ DAC cable.
I haven't been able to figure it out. The 'slower' speeds are still great, I just don't understand why it can't achieve more than 1.5Gbps down over a 2.5Gbps network connection.
Any ideas?
Can you test without the MikroTik? I've been having similar issues with my Mikrotik set up (I had a half a dozen or so posts on reddit about it). It appears the devices are not handling flow control correctly and the buffers are being overwhelmed. I'd test first without the Mikrotik and then experiment with flow control on the port. Be aware that you seem to have to disable and reenable the interface for flow control to take effect (or reboot). It has been getting better with more recent versions of RouterOS but it is still not "right" it used to be much much slower.
Edit: fixed a typo