Just installed OpenWrt, everything works fine except my download speed is almost halved

Hi,

I have a Netgear R7800 router and successfully installed OpenWrt by watching a youtube video. I set up everything right(always wired connection) but when doing speed tests I'm supposed to get 300mbps download and 30mbps upload, after setting up openwrt my download speed sunk to around 190mbps while upload speed remained the same.

I have my modem setup as a bridge but just to test it out I took it out of bridge mode and made a direct connection and my speed was back to 300mbps like it should, so that was not the problem. Is there something I missed during the installation?

Well first test is to figure out if the speed loss is between the client and the router, the router and the internet or by the firewall/nat on the router.

For that suggest to install iperf3 on the router and your client to first test the plain speed between them.
Next step would be install speedtest-cli on the router to test speed between router and the internet.

Thank you for your reply. I tried to look up how to install iperf3 on my router and client but it's beyond me. I managed to install speedtest-cli from the openwrt software tab but I don't see a way to actually use the speedtest.

This usually won't give you any meaningful information. Running iPerf on most standard consumer routers will not give results that represent the actual routing speeds because the test will be limited by the SoC in the router (which is not very powerful and cannot generate/terminate packets very efficiently). Routers are purpose built to route traffic (meaning the traffic passes through the device) using specialized hardware, and the router isn't responsible for generating or terminating that traffic. A router that can easily route at 1Gbps may only be able to do an (onboard) iPerf test at around 250Mbps, as an example (I can think of several such devices).

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Well he has problems with 190mbps versus 300mbps in that range iperf3 on a current router should be able to be used for troubleshooting.

Did you access your router via SSH? Than that should be straight forward also the installation/usage of iperf3.

Same here. I just get back to openwrt 19.08.
I got 1000M broadband, if using openwrt 19.07, speedtest.net or fast.com test got 800M download speed. Using openwrt 21.02, only 500M download speed. The speed test is using default configuration.

You can try openwrt 19.07 version.

Thank you I will try this out. Which version of 19.07 should I use? The oldest one 19.07.4? Or the newest one 19.07.8?

Edit: Ok I tried it but sadly it didn't work. I tried different builds as well and no dice....

I searched Openwrt forum again, there is a solution. Enable Network→Interface→ Global network options→Packet Steering. And Network→Firewall→Software flow offloading and Hardware flow offloading in Openwrt 21.02. I got my full download speed back. Hope this is helpful.

I upgrade to openwrt 21.02 today. At least, it works for me.

You might check what that did to your bufferbloat...

Also, if you use IPv6, hardware flow offloading causes connection instability.

Oh, right. I also disable IPv6. Network→Interface→Devices, uncheck "Enable IPv6" for every device.

I tried everything out and even did them one by one and sadly no change. My upload speed is as it's supposed to be, but my download speed is the one that is suffering. It's at 190mbps when it should be 300mbps.