Pretty bad speed when using RPi4 + router

Installing and Using OpenWrt
1

I'm setting up my network as:

ISP router (in bridge mode) -> RPi 4b (managing the PPPoE connection) -> Archer C2600 (as a dumb AP)

I use an Archer C2600 to distribute the wifi, however it doesn't have anything on, all network is managed by the RPi.

My internet connection should be 600Mbit/s. Testing the connection on the RPi I get around 520Mbit/s which is pretty good. When I test on the AP I get around 240Mbit/s, which is not that great.

How am I losing so much speed?

RPi has Packet Steering on and irqbalance on too. Should I enable them on the Archer too?

Both RPi and Archer are running v21.02.3

2
  1. never seen any AP which actually would deliver the official spec's number.
  2. wifi speed is dependent on many factors: such as client (not necessarily the AP is slow), interference (neighbor using same channel), your physical surroundings (type of wall), proximity to AP, gain of antenna (AP and client) etc etc etc
  3. not sure how you measure but there maybe heavy traffic in the background you don't think of (OS patching)

try to move the AP around, you may find a spot which is better.

3

Install default firmware for your Archer and test again. On RPi4 I get more than 900mbps speed on latest snapshot but on it's wifi its reduced to 90mbps. I don't know why

4

On the Pi's wifi? This would be expected... the wifi chipset on the Pi is really low end and is not capable of high bandwidth performance. The Pi4 makes an excellent wired router, but the wifi should be disabled and a real AP should be used to provided wifi services.

5

What channel and frequency? How much congestion on that frequency? What are you using as a client? (Make, model, year, operating system, etc.). What is the distance between the client and AP, and are there any intervening walls or objects? Are there any other WIFI clients connected to the same AP while you're testing?

WIFI speeds are hugely dependent on the client, other concurrent clients (even if they're not using much bandwidth, the AP is using resources to maintain the connection). WIFI speed tests are almost meaningless except under carefully controlled conditions: over short distances, unimpeded line of sight, on channels without significant nearby interference.

6

Thanks all for the quick replies.

To clarify, I'm not testing using wireless. Both devices (RPi and Archer) are using OpenWRT and I tested using this lib https://openwrt.org/packages/pkgdata/python3-speedtest-cli

So, when testing on RPi the speed is 520Mbit/s, and when testing on Archer (which is connected by cable to the RPi) the speed is 240Mbit/s

I'm using a gigabit USB adaptor (https://www.tp-link.com/en/home-networking/computer-accessory/ue300/) to connect the external modem to the RPi, and the internal ethernet to connect the RPi to the Archer.

So the speed is lost from the RPi to the Archer

7

What is the CPU utilization on the Archer during the test? Could be a bottleneck from running the test on on underpowered device.

1 Like
8

Did you try installing Tplink firmware on your Archer? That might solve your issue.

9

The CPU scheduler tuning on ipq806x devices like the C2600 is sub-optimal - see the R7800 performance thread for more details and ways to adjust the scheduler (the R7800 is clocked at 1.7GHz clock while the C2600 is clocked at 1.4GHz but otherwise the info is relevant).