The 15 inch MacBook Air with the M4 chip supports Wi-Fi 6E, which adds the 6 GHz band, and its Wi-Fi faults are different from older Airs because of that. A router that broadcasts 2.4, 5 and 6 GHz under one name can leave the Mac on a band it handles badly, so test with separate names. The 6 GHz band has shorter range, so a Mac in another room falls back to 5 GHz and may drop during the switch. Check the signal by holding Option and clicking the Wi-Fi icon in the menu bar, which shows the band, channel and speed, and run Wireless Diagnostics as Apple describes.
Apple's page for a Mac that is not connecting gives the sequence: confirm Wi-Fi is on, restart the router and the Mac, forget the network and rejoin.
The checks in more detail
The M4 Air has Limit IP Address Tracking and Private Wi-Fi Address settings that some routers dislike; turning off the private address for that network in Wi-Fi, Details, can help with filtering. VPNs and content filters are other causes of pages that will not load. Wi-Fi's menu icon also tells you whether the Mac sees the 6 GHz network: if the network does not appear, the router may need its 6 GHz band enabled or its region setting changed, and some routers disable 6 GHz by default.
Checking the router's own app shows whether the band is on. If the Mac connects at the router but is slow in a specific room, run a speed test in that room and compare it with the router's room; a large difference means coverage, and the cure is a mesh node, not a Mac setting. Keep the Mac's macOS and the router's firmware current so new Wi-Fi features work together.
Differential
Likely causes of “Apple MacBook Air 15-inch will not connect to Wi-Fi or keeps disconnecting”, and how to tell them apart
- 1
A router merging 2.4, 5 and 6 GHz
What separates it The Mac hangs on a weak band
How to confirm Give each band its own name and join the right one
- 2
A move between 6 GHz and 5 GHz
What separates it Drops when you change rooms
How to confirm Place a node nearer or use 5 GHz
- 3
A Private Wi-Fi Address filter
What separates it The router refuses the Mac
How to confirm Turn off Private Wi-Fi Address for that network
- 4
A VPN or content filter
What separates it Pages fail only with it on
How to confirm Disable it to test
- 5
A stale network entry
What separates it Repeated failure to join
How to confirm Forget and rejoin
Before you touch a setting
Record this first — changing settings destroys the evidence
- The band, channel and speed from the Option-click menu
- The router model and its band setup
- Whether a VPN is on
- Whether other devices work
Try in this order
0 of 8 completedOption-click the Wi-Fi icon
ReversibleNote the band and speed.
Separate the router's bands
ReversibleGive 2.4, 5 and 6 GHz separate names.
Run Wireless Diagnostics
ReversibleFrom the Option-click menu.
Check Private Wi-Fi Address
ReversibleIn Wi-Fi, Details, for that network.
Turn off a VPN
ReversibleTo test.
Forget and rejoin
ReversibleWith the password.
Check whether the router has 6 GHz on
ReversibleIn the router's app, make sure the 6 GHz radio is enabled.
Check the router's region setting
Reversible6 GHz depends on the router being set to the right region.
Model-specific
What is true of this model and not of its siblings
- Three bands
- The M4 Air can use 2.4, 5 and 6 GHz.
- Private address
- Some routers filter by address.
- 6 GHz off by default
- Some routers leave it off.
- Regions
- Rules for 6 GHz differ by country.
Stop boundary
When this stops being a self-service repair
- !If Wireless Diagnostics reports faults on several networks, contact Apple Support
- !If only one router fails, update its firmware
- !Save the diagnostics log
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Does the M4 Air support Wi-Fi 6E?+
Yes.
What is 6 GHz?+
A faster, shorter-range band.
Why does my Mac drop when I change rooms?+
It switches bands.
What is a private address?+
A random address used on each network.
Why can't my Mac see my 6 GHz network?+
The router may have it off.
Does the M4 Air need 6 GHz?+
It works without it.