spdMerlin spdMerlin download speeds halved

irp21

New Around Here
Hello all,
I recently installed spdMerlin and found that its speedtests are not correct. It shows my 1Gbps connection WAN speed is halved. Upload speed is closer to what I expect.

spdMerlin set up excluded from QoS, on v4.4.4, haven't touched autoBW as I don't know what that does, using built-in ookla speedtest returns the average following speeds.
Download: 457.18 Mbps (data used: 828.4 MB )
Upload: 758.25 Mbps (data used: 859.3 MB )

When I run Ookla's cli speedtest from a linux box wired to a LAN port on this AX88U I get what seem to be more accurate speeds. Both are going to the same speedtest server.
Download: 916.79 Mbps (data used: 677.8 MB )
Upload: 938.63 Mbps (data used: 458.0 MB )

I'm guessing is that its some sort of configuration issue, maybe autoBW. I haven't made changes to this section and its set to default(disabled).
 

Viktor Jaep

Very Senior Member
@irp21, this is unfortunately a well documented issue. You're running into a CPU limitation on the router itself, and can't accurately handle or display speeds for people with bandwidth greater than about 400-500Mbps. It works great for folks with lower ranges of bandwidth. But what you did is probably the best test, by hooking up a separate computer directly to the router LAN port itself.
 

visortgw

Very Senior Member
Hello all,
I recently installed spdMerlin and found that its speedtests are not correct. It shows my 1Gbps connection WAN speed is halved. Upload speed is closer to what I expect.

spdMerlin set up excluded from QoS, on v4.4.4, haven't touched autoBW as I don't know what that does, using built-in ookla speedtest returns the average following speeds.
Download: 457.18 Mbps (data used: 828.4 MB )
Upload: 758.25 Mbps (data used: 859.3 MB )

When I run Ookla's cli speedtest from a linux box wired to a LAN port on this AX88U I get what seem to be more accurate speeds. Both are going to the same speedtest server.
Download: 916.79 Mbps (data used: 677.8 MB )
Upload: 938.63 Mbps (data used: 458.0 MB )

I'm guessing is that its some sort of configuration issue, maybe autoBW. I haven't made changes to this section and its set to default(disabled).
As another data point, I had the same experience with my RT-AX88U connected to Spectrum's 1Gbps down/35 Mbps up. Once I "upgraded" to an RT-AX86U as my primary router, I configured the router's 2.5Gbps port as its WAN port — the Spectrum-provided modem has a matching 2.5Mbps WAN port as well. My WAN speeds from both spdMerlin and the router's built-in speed test under the Adaptive QOS tab have increased by 200Mbps or so. FYI, I do not currently use adaptive QOS as I have not seen any benefit in my tests given my connection speeds.
 

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doczenith1

Very Senior Member
My AC86U over a FTTH non-PPPoE gigabit connection running 386.5 with Runner: Enabled - Flow Cache: Enabled just got the following.

1646684588109.png


Looking at the older values on pre-386.5 firmware my max speeds were around 600 Mbps.

Edit: Just to be clear, this is using the firmware GUI test and not the script.
 

Jack Yaz

Part of the Furniture
My AC86U over a FTTH non-PPPoE gigabit connection running 386.5 with Runner: Enabled - Flow Cache: Enabled just got the following.

View attachment 40036

Looking at the older values on pre-386.5 firmware my max speeds were around 600 Mbps.

Edit: Just to be clear, this is using the firmware GUI test and not the script.
spdmerlin can use the same speedtest app the GUI one does, so the results should be identical
 

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