Situation: a Linksys WRT1900AC router is running DD-WRT v3.0-r57834 std (08/10/24). With stock settings, the AC (5 GHz) wireless connection delivers a throughput of approximately 120 Mbps (tested using iperf3). Here's how the throughput changed when we changed some of the settings (all settings mentioned here are on the Wireless >> Basic Settings page in DD-WRT).

1. Change Channel from Auto to 36: 160 Mbps
2. Change Channel again, this time to 120: 190 Mbps
3. Check the Advanced Settings box and change both TX antenna chains and RX antenna chains to 1+2: 390 Mbps