AC-3200 bad jitter on wifi but not wired LAN

[BHackbarth]

Hey everyone, I just bought an AC-3200 and installed Merlin's 384.13. I've been at this for many years at home and at work but now I'm stumped. I'm on clean channels (no overlapping), inssider link score of 100, have WMM enabled (it's on by default anyway), followed Merlin best practice guides for the other wireless professional settings, etc. However, even a foot away from the antennas, wifi connections get terrible jitter between 300ms up to 800ms with no other heavy traffic on the WLAN (just a couple of idle Alexa devices). Wifi calling is unusable, even if I place a call from my smartphone to a voip server on my own LAN. I ran voip quality testing software through the wired lan and then through 2.4G and 5G wireless and graphed - wired LAN was perfect MOS 4.0 the whole time but Wifi barely made 2.5 - 3 and audio gaps occurred with each latency spike. Both bands, 2.4 and 5Ghz have the problem. I switched back the janky AT&T BGW210-700 and wifi calling is instantly usable through that (same channels as the Asus). But I'd like to have that in IP Passthru and use the Asus for its many additional config options. I tried the factory Asus firmware (plus a factory reset) but was not surprised the behavior was the same. Browsing the config pages in the Asus seemed to be able to make the problem worse, but the CPUs were not very busy according to the graphs.

Is my hardware defective or did I misconfigure something?

 

[sfx2000]

However, even a foot away from the antennas, wifi connections get terrible jitter between 300ms up to 800ms with no other heavy traffic on the WLAN (just a couple of idle Alexa devices). Wifi calling is unusable, even if I place a call from my smartphone to a voip server on my own LAN

Look at things from more than 1 meter away from the AP...

 

[BHackbarth]

Look at things from more than 1 meter away from the AP...

Thanks for the reply! If only it were that easy. I did narrow it down to iPhone chipsets. My old Samsung s6 works properly but my iPhone 8 and my wife’s 8 plus get horrible packet loss. My old asus ac 66u works fine with all devices. My old linksys worked as well. Not sure if there is something I can disable in the pro settings or if the chipsets just don’t get along. Packet loss is up to 50% on iPhones and normal 5% on the Samsung, any distance from radio, any band, any channel, any channel width.

 

[BHackbarth]

I just discovered that changing the wireless mode to Legacy results in perfects calls. N only / AC + N mixed and Auto all produce the issue. Narrowing to 20Mhz and keeping the channel did not do the trick, I had to get away from N and AC. I think that means I will not be using this router. Something in the iphone wifi chip does not seem to like N and AC modes on this router.