RPi4 router, slow speeds. How to diagnose?

Add

force_turbo=1
arm_freq=1600

to /boot/config.txt and reboot. Maybe also enable software offloading in the firewall. Beyond this there could just be something aberrant in the install. RPi4 can and should be able to route close to a gigabit without SQM and VPN. I'd recommend wulfy's build for a solid base.

thanks for your help. (i had already activated software offloading)
those config settings didn't help.
i'll try installing wulfy's build when I have some permissible network downtime to do it.

thanks again.

I use a snapshot from mid-march 2021 as my default router for gigabit fiber WAN and several gigabit internal VLANs. Straight out of the box and without tuning I can get simultaneous gigabit throughput across several ports. With tuning (raising the minimum CPU freq to 1GHz, manually distributing the interrrupt core affinities with a script) I get that without the CPU ever going over 10% on any core.

I agree with what @anon50098793 says above: your problem is probably not Pi related and I don't think using one of his builds is going to fix it. What kind of switch is it connected to?

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Forgive me if this is obvious, but do the port LEDs on the switches indicate a 1000mbps link in every case?

If you're testing from Ethernet perhaps the issue is the connection between your computer and the switch, and nothing to do with the Pi at all.

Try swapping out cables from computer to switch, and also try checking the info on the NIC connection from your computer

Another option is maybe some windows firewall junk if you're using a windows computer for testing

Connect any computer directly, using cable, to the RPi, and rerun the test...

Bypass the switches in between...

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Nope. Same deal. maxes out around 100-115 mbps.

Tested using what, iperf?

And if you run top or nmon during the test, does it max out any of the CPU cores?

For the fun of it, try swapping the ports, make the USB NIC LAN, and vice versa.

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cat /sys/kernel/debug/usb/devices | grep -C13 r8152

Don't enable software offloading on the Pi - only use irqbalance (and make sure it's actually working - counters for IRQ 31 should be on CPU 1, IRQ 32 on CPU 3, and IRQ 39 on CPU0),

You need to check the computer you're using for the test and the Ethernet cable it's using.

The Pi itself, if nothing is borked, can route and SQM a gigabit so it's not the bottleneck unless there's a cable issue or it's got a physical problem like an altered CPU clock speed limit

[deleted deleted]

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this my friend ain't looking good...

It's either a USB2 dongle, or it's on a USB2 port.
Easiest thing is to unplug and then re-plug making sure to put it in one of the BLUE colored ports. If it still says Spd=480 then it's not a USB3 dongle.

make sure it's actually working - counters for IRQ 31 should be on

how would i go about checking that...? :slight_smile:

I swear to god it's on the blue ports.

but I... did not get a brand name dongle. I will acquire a new one and try again.

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The UE300 from TP-Link is the most common one recommended based on the benchmarks I put up in the thread from last year. Also quite inexpensive.

cat /proc/interrupts

Well, it definitely means irqbalance either isn't installed or isn't enabled/running. That's the whole point. :slight_smile:

Ok. Weird update:

speedtest through xfinity (my isp): says i'm at my paid-for speeds of 600 mbps
speedof.me: 100 or so mbps on wired, ~250 mbps on wireless.
iperf3 on the router: ~28 mbps
iperf3 on network machine (wireless): ~20 mbps

w... t... f...