ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc

ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc

ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
2026-08-14 07:19:44 - last edited 2 weeks ago
Model: ER605 (TL-R605)  
Hardware Version: V2
Firmware Version: 2.4.5

I have recently installed a brand new ER605 in a new environment. Connected directly to an ISP media converter running Dynamic IP DHCP.

With a hardwire connection to the media converter, I get the rated 1Gbps down/1Gbps up.

Once I installed the ER605, the results were 500Mbps down/1Gbps up.

 

I have tried in standalone and adopted to a software controller.

 

I have tried multiple different Cat6 cables.

I have tried enabling and disabling hardware offload.

I have attempted factory reset and cold boots.

 

I have tried disabling all security features, with no change.

 

I have ensured that no control/qos settings are enabled.

 

I have tried with flow control on and off for the WAN port.

I have been through every single setting and cannot determine the root cause of this issue beyond a faulty device, OR the device itself cannot handle 1Gbps fiber connections.

 

Any joy from the group on resolving a similar issue? I see Reddit chatter, but no joy from those threads.

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#1
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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc-Solution
2026-08-17 16:37:44 - last edited 2 weeks ago

  @Vincent-TP 

Thank you Vincent.

I am unable to run a quick test right now as it's the work week, but on the weekend I should be able to run a test from WAN through to LAN between 2 PC's.

In the meantime, with some quick experimenting I noticed something - Running a UDP test to an iperf server in my locale targeting 1000m connection speed runs at 960m. Running the same TCP test to any available iperf server in my locale maxes at 60Mbit.  The interesting part, to me, is that UDP fully saturated at 960.



 

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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
2026-08-14 13:57:54

Have you tried to configure a different port on the router?  the port could be bad?

 

I can not teach anyone anything - I can only make them think - Socrates
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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
2026-08-14 18:07:51 - last edited 2026-08-14 18:13:41

Yeah, unfortunately same behaviour. I am thinking that somehow hardware offload is being automatically disabled by another feature (DPI is disabled, QoS has no profiles), however, I cannot find anything in the config, even after a force reset, standalone or cloud adopted.

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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
2026-08-17 08:50:48

Hi  @element151 

 

Thanks for posting here.

To determine if this is a hardware issue, you may run an iperf test with ER605. Below is a guide:

 

How to Use iPerf to Test the Speed on TP-Link Routers

 

Note: please run the test with the default settings.

 

If the issue persists, you may contact your retailer for a replacement.

If the iPerf test can reach 1G, don't hesitate to let us know.

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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc-Solution
2026-08-17 16:37:44 - last edited 2 weeks ago

  @Vincent-TP 

Thank you Vincent.

I am unable to run a quick test right now as it's the work week, but on the weekend I should be able to run a test from WAN through to LAN between 2 PC's.

In the meantime, with some quick experimenting I noticed something - Running a UDP test to an iperf server in my locale targeting 1000m connection speed runs at 960m. Running the same TCP test to any available iperf server in my locale maxes at 60Mbit.  The interesting part, to me, is that UDP fully saturated at 960.



 

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#6
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Re:ER605 50% Download Speed Out of Box Regardless of Settings, Standalone Etc
2026-08-31 07:19:40

Hi  @element151 

 

Thanks for the reply.

Did you get time to run the test on the router? What's the result?

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#7
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