How to Fix Slow WiFi on MacBook Pro M4: Wireless Adapter, Network Profiles, and Driver Fixes

The MacBook Pro M4 ships with a capable WiFi 6E radio, yet many owners find their wireless speeds lagging far behind what other devices on the same network achieve. The culprit is rarely the hardware itself — it is almost always a software misconfiguration, a corrupted network profile, or an unexpected source of physical interference specific to Apple Silicon machines. Work through the fixes below in order and you will likely resolve the problem without visiting an Apple Store.

Fix 1: Delete and Recreate Your WiFi Network Profile

macOS stores a preference file for every WiFi network you have ever joined. Over time — especially after a major macOS upgrade like Sequoia — these profiles can become corrupted, causing the wireless stack to negotiate a lower link rate or repeatedly drop and rejoin the network.

How to Remove a Stale Profile

1. Open System Settings → Wi-Fi.
2. Click the Details button next to your network name.
3. Scroll to the bottom and click Forget This Network.
4. Repeat for any duplicate entries of the same SSID (common after router firmware updates that change the network name slightly).
5. Rejoin the network, entering your password fresh.

For a deeper clean, you can also delete the stored keychain entry: open Keychain Access, search for your network name, and delete the matching entry before rejoining.

Fix 2: Disable Private Wi-Fi Address (Rotating MAC)

macOS Sequoia introduced rotating private Wi-Fi addresses by default. While good for privacy on public networks, this feature can confuse home routers — particularly older or budget models — that attempt to maintain a DHCP lease tied to a specific MAC address. The result is repeated IP assignment conflicts that throttle your effective throughput.

Go to System Settings → Wi-Fi → Details next to your network, then change Private Wi-Fi Address from Rotating to Fixed or disable it entirely. Reconnect and retest.

Fix 3: Eliminate USB 3.0 and Thunderbolt Interference

This is the most surprising cause of M4 MacBook Pro WiFi slowdowns and one that trips up even experienced users. USB 3.0 and Thunderbolt 4 devices emit broadband RF noise that falls directly on the 2.4 GHz WiFi band and, in some cases, the lower 5 GHz channels. Because M4 MacBook Pros integrate the WiFi antenna very close to the chassis edges where docks and cables connect, the interference path is short and the effect is severe.

How to Diagnose

1. Disconnect all USB, Thunderbolt, and HDMI cables from the MacBook.
2. Run a speed test on our WiFi speed tool. Note the result.
3. Reconnect devices one at a time and retest after each addition.
4. The device that causes a speed drop is your interference source.

How to Fix

• Switch to a shielded HDMI or Thunderbolt cable. Cheap cables with poor shielding are the most common offender.
• Use a powered USB hub with a ferrite bead on the cable rather than plugging directly into the MacBook.
• Force the MacBook onto 5 GHz or 6 GHz. USB 3.0 interference is almost entirely limited to 2.4 GHz. See our guide on how to connect to the 5 GHz band.
• Reposition your dock or hub further from the MacBook when on battery-powered tasks requiring peak WiFi throughput.

Fix 4: Renew DHCP Lease and Set a Fast DNS Server

A stale DHCP lease can cause the MacBook to hold an IP address that the router has already reassigned, leading to packet collisions and dramatically reduced real-world speeds even when the link rate looks fine.

1. Go to System Settings → Wi-Fi → Details → TCP/IP.
2. Click Renew DHCP Lease.
3. Switch to the DNS tab and add 1.1.1.1 (Cloudflare) and 8.8.8.8 (Google) if the list is empty or shows only your ISP’s servers. Cloudflare’s resolver is consistently the fastest globally and reduces the first-byte latency on every new connection your browser opens.

Fix 5: Flush the DNS Cache and Reset the Network Stack

macOS caches DNS responses aggressively. After a router reboot, ISP outage, or macOS update, those cached records can point to stale IP addresses, making websites appear slow even though your raw download speed is fine.

Open Terminal and run:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

Then, to fully reset the wireless stack without a full reboot, turn Wi-Fi off in System Settings, wait 10 seconds, and turn it back on. This is the software equivalent of pulling the adapter.

Fix 6: Disable the macOS Firewall Temporarily to Test

A known macOS Sequoia bug causes the built-in Application Firewall to rate-limit certain outbound connections under specific network conditions, which can manifest as inexplicably slow speeds on speed tests while latency remains low. To test: go to System Settings → Network → Firewall and toggle it off, then run a speed test. If speeds jump significantly, re-enable the firewall and check the Block all incoming connections option is not checked, as that setting is overly aggressive for home networks.

Fix 7: Update macOS and Check for Wireless Firmware Updates

Apple ships WiFi driver improvements as part of macOS point releases. If you are not on the latest version of macOS Sequoia, go to System Settings → General → Software Update and install any pending updates. The M4 MacBook Pro received targeted WiFi stability patches in Sequoia 15.2 and 15.3 that addressed link-rate negotiation bugs with WiFi 6E access points.

Fix 8: Run Apple Diagnostics

If speeds are still poor after all the above steps, the wireless hardware itself may be at fault — antenna cables can work loose during shipping, and the M4 Mac Mini in particular had a documented batch with suboptimal antenna contact. To check:

1. Shut down the MacBook completely.
2. Power it on and immediately hold the D key until the Apple Diagnostics screen appears.
3. Follow the on-screen instructions. A WFB error code indicates a WiFi hardware failure.

If Diagnostics returns an error, make a Genius Bar appointment — the repair is covered under the standard one-year warranty or AppleCare+.

Quick Checklist

• Forget and rejoin your WiFi network to clear corrupted profile data
• Set Private Wi-Fi Address to Fixed instead of Rotating
• Unplug USB 3.0 and Thunderbolt devices and retest to isolate RF interference
• Renew DHCP lease and switch DNS to 1.1.1.1 / 8.8.8.8
• Flush DNS cache via Terminal: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
• Temporarily disable macOS Firewall to rule out Sequoia rate-limit bug
• Install latest macOS update for WiFi driver patches
• Run Apple Diagnostics (hold D at boot) to rule out hardware faults

Once you have worked through these fixes, run a speed test to confirm you are getting the full speed your plan provides. If speeds are still inconsistent across devices, the problem may be your router rather than the MacBook — see our guide on why WiFi speed varies between devices for more.