Proper WAN download speed but very slow WAN upload speed

[xpspectre]

Hello everyone! I've got a DEC840 running OPNsense 21.4.1-amd64 that's showing strange behavior on a 1 Gbit/s down/1 Gbit/s up internet connection. The WAN port is connected via a regular 1000base-T port to the upstream ISP, and I've confirmed that I get gigabit speeds in both down/up when directly plugged into my computer. However, using the OPNsense device, I get the expected down speed but very slow up speed, ~1-3 Mbit/s. This happens with more or less the default starting configuration with 1 WAN and 1 LAN port. I've tried things like trying the other ports and explicitly setting the connection to 1000base-T full duplex instead of the default autonegotiate and no luck. Any ideas? Thanks in advance.

[spaxxilein]

Have you checked CPU-usage with top in the CLI?

[xpspectre]

Thanks for helping troubleshoot! Actually, I fixed (well, more specifically, worked around) the upload slowness issue. The ultimate issue stemmed around the SFP+ ports on the DEC840 - using them at all seems to cause all-around issues: slow speeds in 1 direction, inability to use 1 Gbit SFP modules, etc. Trying all the combinations of ports indicated the SFP+ ports were the culprit. Totally disabling them cleared everything up, but now we're limited to 1 Gbit/s even when routing between internal nets. This is an acceptable workaround for now. The 1000base-T ports seem to work properly when solely using them.