Why Sequoia 15.5 breaks Wi-Fi on many MacBooks
Short answer: macOS Sequoia 15.5 overhauled the mDNSResponder daemon — the background process that handles network discovery and local device detection. The update also tightened how Network Extensions (VPNs, firewalls, privacy tools) interact with the Wi-Fi stack. On routers that broadcast both 2.4 GHz and 5 GHz under a single SSID — common across Indian ISPs like Airtel, Jio Fiber, and BSNL — this creates a band-steering conflict that drops the connection every few minutes. The fix is almost always software, not hardware, and takes under ten minutes.
How to fix macOS Sequoia 15.5 Wi-Fi disconnects
Step 1: Flush the preferred networks list
Your Mac remembers every Wi-Fi network it has ever joined, along with channel and security preferences. After a major OS update, some of those stored preferences conflict with the router's new handshake. Go to System Settings → Wi-Fi, click the Details button next to your network, and scroll to Forget This Network. Then re-join from scratch. For a more thorough flush, open Terminal and run:
sudo networksetup -removeallpreferredwirelessnetworks en0Replace en0 with your Wi-Fi interface name (confirm with networksetup -listallhardwareports). Reconnect to your network and test for 10 minutes. This alone resolves the issue for roughly half of users who report Sequoia 15.5 disconnects on Indian routers.
Step 2: Remove conflicting Network Extensions
VPN apps, firewall tools (Little Snitch, CleanMyMac, Malwarebytes), and some Indian ISP utility apps install Network Extension kernel modules that hook into the Wi-Fi stack. Sequoia 15.5's stricter extension handling can cause these to stall the connection. Go to System Settings → General → Login Items & Extensions, scroll to Network Extensions, and toggle off anything not essential. Reboot and test. If Wi-Fi stabilises, re-enable extensions one by one to identify the offender.
Step 3: Reset mDNSResponder and DNS cache
If the disconnects continue, the mDNSResponder process may be holding stale DNS or Bonjour (local device discovery) records. Open Terminal and run:
sudo killall -HUP mDNSResponder
sudo dscacheutil -flushcacheThen restart your Mac. On M2 and M3 MacBook models, also reset NVRAM (the small memory chip that stores hardware preferences) by holding Option + Command + P + R at startup until you hear the second chime or see the Apple logo twice. NVRAM reset clears the Wi-Fi band preference and forces the Mac to negotiate fresh channel settings with the router.
Step 4: The India angle — ISP router firmware and monsoon humidity
A pattern specific to India: many Airtel and Jio Fiber ONT routers (the box the ISP installs) ship with outdated firmware that does not correctly implement the 802.11ax (Wi-Fi 6) band-steering protocol. When Sequoia 15.5 requests a band switch, the router drops the session entirely. Log into your router's admin panel (usually 192.168.1.1) and check for a firmware update under Maintenance or Advanced settings. Updating the router firmware resolves the disconnect for roughly 30% of Indian users where the Mac-side fix alone did not fully work.
Monsoon humidity is a secondary factor. High humidity accelerates oxidation on the Wi-Fi antenna connector inside the MacBook — a problem we see at our Secunderabad bench from June through September. If you notice the issue worsening during rainy days specifically, the antenna contact may need cleaning. See our guide on macOS Wi-Fi connection issues for the full hardware diagnostic steps.
When to call a laptop repair service
When software fixes stop working
If the Wi-Fi drops within seconds of reconnecting even after all three steps above, or if the Mac shows the Wi-Fi icon as connected but passes zero traffic, the antenna hardware is the likely culprit. Other signs: Wi-Fi signal strength is consistently one bar even when the router is in the same room, or Bluetooth works fine but Wi-Fi is erratic (they share the same antenna assembly on many MacBook models).
Typical repair cost in India
A Wi-Fi antenna card replacement on MacBook Air M2/M3 runs ₹2,500–₹4,500. On MacBook Pro models where the Wi-Fi chip is embedded in the logic board, the repair is more involved and costs ₹6,000–₹12,000. A ₹149 doorstep visit confirms which applies before any commitment.
Step 5: Create a new Wi-Fi network location profile
macOS stores network configurations in Location Profiles — a macOS feature that lets you save different network settings for different environments. A corrupted default profile can cause persistent Wi-Fi issues even after NVRAM reset and network flush. Create a fresh profile: go to System Settings → Wi-Fi → (...)→ Locations → Edit Locations, click the plus (+) button to create a new location named "Home" or "Office", and switch to it. Reconnect to your Wi-Fi network under the new profile. The old corrupted profile can be deleted afterwards. This step resolves persistent Wi-Fi issues that survive individual network setting changes because it creates a completely clean network configuration slate — particularly useful on MacBooks that have connected to dozens of different networks (hotels, co-working spaces, airport lounges) and accumulated a cluttered profile.
A note from the LRW Engineer Team
We see a spike in "MacBook Wi-Fi broken" calls every time Apple ships a major Sequoia point release. Almost none of them turn out to be hardware on first inspection. Walk the three software steps first — especially the NVRAM reset, which many guides skip. Check the Apple MacBook service page if you need a quick walkthrough on which model you have and what a hardware repair involves.