[attfuzz]

So, Iv'e just started using dd-wrt again. Previous router was a Linksys that worked great till you could no longer log into it and it is not supported by dd-wrt. So, went with an Asus RT-AC68U running the 44340 firmware. My issue is with the speeds, they are almost cut in half. With the Linksys on 1GB service, speeds were around 940MB and when on 500MB service, speeds were around 550MB down, our ISP over provisions by 10%, except for the GB speed. Iv'e tried two other dd-wrt firmwares with the same results. Is this all this router is capable of, or am I missing a setting somewhere? Haven't tried the SFE setting yet. Is there a router that will handle the GB speeds running dd-wrt? Model, make, etc. Sorry for so may questions. Thanks.
Edit: did try the SFE setting and it does help, anything wrong with leaving this enabled?
Edit again: now with SFE enabled, wireless speeds are horrible, guess I'll keep messing with it.

[msoengineer]

There is nothing wrong with running SFE.

Your wifi settings are a result of something else being off in the wifi settings and not SFE.

The RT-AC68U was normally good to about 750mbps on stock firmware. With SFE turned on you should be able to hit that Wan-Lan.

In terms of wifi- 2.4ghz will be a crapshoot and you will top out around 90mbps under HT40mode with a client running HT40mode too.

5ghz performance should be around 250mbps max if all your settings are right.

https://www.smallnetbuilder.com/wireless/wireless-reviews/32239-ac1900-first-look-netgear-r7000-a-asus-rt-ac68u?showall=&start=2

[attfuzz]

After some research and playing with some settings, here's what worked for me on a 500 MB download and 125 MB upload from our ISP. Our ISP also over provisions by 10%. This is on the: Firmware: DD-WRT v3.0-r44340 std (09/10/20).

Under Setup, Basic Setup: Set Shortcut Forwarding Engine (SFE) to Enable. This is a must!

Under Wireless, Basic Settings, wl0 2.4 GHz: Wireless Channel: Select a channel that is clean with no overlapping signals from other AP's in the area. Mine was channel 11. Can be "seen" using the WiFi Analyzer App on a phone.

Channel Width: 20 MHz
TurboQAM: Enable
Explicit Beamforming: Enable
Implicit Beamforming: Enable

wl1 5 GHz
Wireless Channel: A good clean channel with no overlapping signals from other AP's around you. Mine is channel 100.
Channel Width: VHT 80
Explicit Beamforming: Enable
Implicit Beamforming: Enable

Wireless Security: WPA2-PSK (AES) on both 2.4 and 5 GHz.

WL0 Advanced and WL1 Advanced
CTS Protection Mode: Disabled
WMM Support: Enabled

NAT/QoS, UPnP, UPnP Service: Enable
NAT/QoS, QoS, Start QoS: Disable

Everyting else is at the defaults. On 2.4 GHz I get around 80 MB up and down. On 5 Ghz I get around 340 MB down and 136 MB up. On a wired connection it's 550 MB down and 136 MB up.