I have 2 Asus TM-1900 routers, set up as (modem -> router -> AP). I have been using this setup with no issues until recently when I upgraded my speed from 300/300 mbps to 500/500 mpbs.

I believe my download speed is being throttled by my secondary router (AP). As a test, I have my desktop connected to the main router, I run a speedtest and get 500/500, Then I make a connection between one of the LAN ports on the AP to one of the LAN ports on the main router, and after a minute or two, the speeds become 300/500 mbps.

Router 1 is subnetmask: default gateway: DHCP enabled IP Pool start: IP Pool end:

Router 2 (AP Mode) is subnetmask: default gateway:

QoS is disabled.

All the cables I'm using cat5e, and the routers have gigabit ports. Is this a limitation of the routers or the network setup?

  • are you connecting through wifi, or you are hardwired to the AP? – RomanK Nov 24 '20 at 1:47
  • @RomanK my desktop is wired to the main router, and the AP is wired to the main router. Everything is hardwired. – Edqu3 Nov 24 '20 at 2:57
  • in this case, the tag is misleading. You are connecting two routers in order Modem->R1->R2. These routers have 1 WAN port(blue) and 4 LAN ports(yellow). How are these connected? – RomanK Nov 25 '20 at 3:40
  • @RomanK modem is connected to R1 WAN port, R1 and R2 are connected via their LAN ports. Desktop PC is connected to either of R1 or R2 LAN ports, this does not make a difference, it always gives me 300/500 mbps. – Edqu3 Nov 25 '20 at 8:52
  • I think we agree this should not be happening, it should work fine. How are you measuring the speed? is it possible to use a tool like iPerf? iperf.fr I would try to measure two devices connected one on each router/AP - That should tell you if you have issues with your internal network. – nycynik Nov 25 '20 at 22:57

If the routers are connected to each other via LAN ports, you have two DHCP servers running on the same broadcast domain, and overlapping subnets.
When the desktop is sending ARP for the gateway, it will get response from both routers...
You can use LAN to LAN connection, the way you have. This way you have single broadcast domain. You need to disable DHCP server on R2. Your WiFi devices will get DHCP leases from the R1. You will need to change R2 subnet to different from R1, so it won't reply to the ARP requests.

  • R2 is already set into AP Mode, this is a feature on Asus router that disables DHCP. Here is more information on the configuration, R1 is and R2 is I'm not concerned with the WIFI access or speed. I am concerned as to why the wired speed drops to 300 when R1 and R2 are connected. – Edqu3 Nov 25 '20 at 17:27
  • @Edqu3 You should add network information to your question. This is not a forum, and we are trying to write questions and answers in a way, so they can benefit other users. Can you also provide information if the issue occurs when R1 QoS is disabled? – RomanK Nov 25 '20 at 21:58
  • I edited my question. QoS was always disabled. @RomanK – Edqu3 Nov 25 '20 at 22:34

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