Internet - Verizon Fios Gigabit, ONT directly connected to WAN port on TP-Link Archer C7 v2 in downstairs room. No Verizon router hooked in (but I have one for a month or two to test with if it's necessary before I go down to the 100 or 300 Mb packages and it isn't free anymore).

Wired LAN - Cat 6 run from main Archer C7 to Archer C9 in upstairs room.

WiFi 1 - Same SSID on 2.4GHz and 5GHz on Archer C7 downstairs. Channels set to 11 40MHz width and 165 Auto Width.

WiFi 2 - Same SSID as WiFi 1 on both 2.4 and 5 GHz, on Archer C9 V3 upstairs. Channels set to 2 40MHz width and 36 80Mhz width.

Both routers are set to high transmit. There is very little interference from other houses, just a couple occasional channels at less than 80 dBm, and then the WiFi direct Fire Stick on whichever it's connected to.

I have two main issues.

1) The upstairs C9 wireless is very slow, on either 2.4 and 5 GHz I'm lucky to get 20 Mbps, and the latency is atrocious, loaded latency of over a second sometimes. Wired to the C9 directly I have hundreds of Mbps up and down and latencies under 30ms loaded.

2) The upstairs C9 5 GHz signal is extremely weak. No matter if I'm 2 feet or 50 feet from it, I'm only getting about 75 dBm. It's overpowered often by even the 5GHz from all the way downstairs.

I did a factory reset of the C9, checked that the firmware was up to date. Neither helped.

When it was the main router (cable comes in there, before I switched to Fios) and I was using WDS to link to the C7 everything seemed fine with the C9.

Even once I swapped where the internet came in but was still using WDS until I ran the cable yesterday, I was getting better speeds from the C9 as the WDS router, it just wasn't super reliable, and obviously not as fast as it could have been.

I'm out of ideas, unfortunately.

  • Given that wired speeds are high and appropriate, try a different wireless AP. I use a Ubiquiti AP for this purpose and get excellent speeds – John Oct 26 '19 at 18:17

Don't use 40MHz width in 2.4GHz. It doesn't leave room for Bluetooth.

Don't use channel 2. Use only channels 1, 6, and 11. Those three don't overlap, and if channel reuse can't be avoided, it's better to be on the exact same channel as another AP rather than partially overlapping it.

Don't use channel 165. It can only do 20MHz width. To get the most out of 802.11ac, you want to use 80MHz (or 160MHz, if supported). Channel 161 should let you do 80MHz width.

Make sure the upstairs C9 is not acting as a NAT or DHCP Server or trying to do WDS or any other form of wireless backhaul/extender/repeater/mesh. It should be acting as a simple AP, bridging traffic between wireless clients and the wired Ethernet LAN connection.

When you were measuring speeds, were you being extremely careful to check which BSSID (the BSSID is the AP's wireless MAC address, not the network name) you had roamed to? If not, then I suspect when you were upstairs you assumed you were on the upstairs AP on 5GHz but you really weren't. Consider using 4 separate SSIDs temporarily while troubleshooting speed issues, so roaming problems don't trip you up.

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  • Moved upstairs 2.4 to channel 1, 20 MHz. Moved downstairs 5GHz to channel 161. Named everything separately. Everything is great except the upstairs C9 5 GHz. Signal strength like -90 even an inch from it, farther than that I can't even get it. Looks like maybe something physically wrong with that radio? – kchinger Oct 27 '19 at 23:38
  • @kchinger. Yep, sounds like the upstairs C9's 5GHz radio is broken, or maybe all of its antennas are disconnected. – Spiff Oct 28 '19 at 0:19

Bad 5 GHz radio in the Archer C9. Being replaced by TP-Link (even though it was technically a couple days outside of warranty by the time I contacted them).

They did a remote connection to play around and check (I guess they didn't believe me) but now it's going back.

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