MacBook Air cannot connect to 5GHz network of AX88U, but can connect to other 5GHz networks

[TakeuchiNonaka]

Hi, I was hoping I could access the brains trust in this forum.

Here’s an overview of my setup and the problem I am experiencing:

Setup: RT-AX88U rev. A.1.1 running latest stock ASUS firmware in wireless router mode connected to the internet via a fibre NTD, broadcasting a 2.4GHz and a 5GHz signal using separate SSIDs and with simple alphanumeric passwords. Stock settings. Netgear R8000 running latest stock Netgear firmware in wired AP mode broadcasting a 5GHz signal using the same 5GHz SSID and password as the AX88U. Also stock settings. The AX88U 5GHz network is on Ch 36 whilst the Netgear 5GHz is on Ch 153.

Problem: Yesterday my mid-2012 MacBook Air could no longer connect to the 5GHz network of the AX88U despite the password being correct – the network credentials are saved in the laptop and Keychain – I also tried entering it manually. I could only connect to the 2.4GHz network. The MacBook Air has a stock 802.11n dual-band wireless adapter. I have left 802.11ax enabled in the router as I have a couple of ax clients and this has not caused issues since yesterday after a couple of months of using the AX88U.

Weirdly enough, I can connect just fine to the 5GHz network of the R8000. I was thinking the 5GHz radio of the MacBook Air may have been failing but the R8000 is actually farther in range and could readily connect via 5GHz. None of my other client devices have connection issues. I flashed Asuswrt-Merlin and did a factory reset. The problem seems to have resolved only to persist again a short while later.

Any ideas or leads would be appreciated.

 

[TakeuchiNonaka]

Update: I noticed the timezones were off on both the ASUS and the Negear so I corrected them. For ASUS the daylight saving start and end dates were flipped and the Netgear was just incorrect (probably because I had set it up as an AP from factory reset so it hasn't connected to NTP). The problem seems to have gone away for now but will continue monitoring. Hat tip to L&LD, I saw this troubleshooting item in one of their posts. It's interesting how mature the wireless technology space is and yet these little quirks can still trip you up.