Posted: Fri Aug 02, 2024 2:17 Post subject: [SOLVED] ASUS RT-N66U: Slow Wired Internet Speeds
I am using an ASUS RT-N66U, which I've upgraded to the latest beta mega build (DD-WRT v3.0-r57707 mega (08/01/24)) using the instructions in the Wiki.
I know this is an older router, but I would still expect to get gigabit speeds over Ethernet. And I do---if I run `iperf` on two different hosts connected to the router via Cat 6, I get ~940 Mbps. However, when checking Internet speeds via speedtest.net, I only get ~320 Mbps. I have gigabit fiber, and I normally get ~900 Mbps on speedtest.net, fast.com, etc.
I've double-checked my Ethernet cables and factory defaulted the router, which didn't help. What other steps would you recommend I take to diagnose this? Is it possible there are firewall, router, or other settings that are slowing speeds over WAN but not LAN?
Sorry, should have checked the forum first---lexridge already provided a fix for this, which is to switch the "Shortcut Forwarding Engine" to CTF under the `Basic Setup` menu.
Now I'm getting upwards of 800 Mbps, which is much more reasonable. WiFi is still dirt slow, but that's as it should be with this router!
As noted by @egc in the thread you referenced, be sure to enable CTF&FA after enabling CTF to squeeze a bit more out of it. _________________ - Linksys EA8500: I-Gateway, WAP/VAP 5ghz only. Features: WDS-AP, VLANs, Samba, WG, Entware - r58819
- Linksys EA8500: 802.11s Secondary w/VLAN Trunk - r58976
- Linksys MX4300: 802.11s Primary w/VLAN Trunk over 5ghz. 2.4ghz WAP/VAP only - r58976
- Linksys MX4300 (WAP/VAP (7)) Multiple VLANs over single trunk port. Entware/Samba r58976
- Linksys MR7350: WDS Station for extended VLANs over Ethernet r58976
- Linksys Velop WHW03v1 x2: OpenWRT w/GRETAP tunnel for VLANs on VAPs
- OSes: Fedora 39, 9 RPis (2,3,4,5), 20 ESP8266s: Straight from Amiga to Linux in '95, never having owned a Windows PC.
After rebooting I don't see FA as an option below "Short Cut Forwarding Engine" (no QoS or Firewall enabled), so I'm guessing this router doesn't support it.
Now I'm getting upwards of 800 Mbps, which is much more reasonable. WiFi is still dirt slow, but that's as it should be with this router!
If you're still running this, what speeds are you getting for Wi-Fi? I tested DD-WRT on an RT-N66U last year and got 50 Mbps max download speeds on 5GHz, which prompted me to switch straight back to John's MerlinWRT fork where I was getting 180 Mbps. Now I'm wondering if the fix you mention above would've helped.
