Router Keeps Rebooting? Fix the Overheating and PSU First

The Short Version: What Actually Causes This

Your router rebooting every few hours has two common causes — overheating or a dying power supply. Most people waste time on firmware updates and factory resets first. Don't. Start with the hardware. I've seen this on TP-Link Archer C7s, ASUS RT-AC68Us, and Netgear R7000s running stock firmware, DD-WRT, or OpenWrt. The fix is the same.

Step 1: Kill the Heat

Routers are basically tiny computers without fans. When they run hot enough, the CPU throttles down, then crashes, then reboots. That's the reboot cycle you're seeing. The fix is simple: get it off the carpet, out of the cabinet, away from your cable box. Put it on a hard surface with some air gap underneath. If it's still hot to the touch after running for an hour, point a small USB fan at it. No joke — that'll stop 80% of these reboots.

What's happening here is the SoC (system-on-chip) hits a thermal threshold around 85-90°C on Broadcom or Qualcomm chipsets. The firmware has a watchdog timer that resets the board when CPU temps spike. If you log into your router's admin page and watch the CPU temperature under Tools or Status, you'll see it climb before each reboot. My ASUS RT-AC68U used to reboot at 92°C. A 120mm USB fan dropped it to 52°C — never rebooted again.

Step 2: Swap the Power Supply

If it's not heat, it's the PSU. Router power bricks are cheaply made. After a year or two, the capacitors start leaking or drying out. The output voltage drops under load, and the router browns out, then reboots. You'll usually see this happen more when the router is handling traffic — like when you're streaming or gaming. That's because the PSU can't deliver the current it needs when the Wi-Fi radios and CPU crank up.

Test it: grab a multimeter, set it to DC voltage, and probe the barrel jack while the router's running. You should see exactly the voltage printed on the brick (usually 12V or 9V). If it's below that by more than 0.3V, replace it. Or just buy a new brick — they're $8 on Amazon. Make sure the polarity is center-positive (most routers are). I keep a spare 12V/2A brick for testing. It's saved me hours twice.

Step 3: Check the Cable and Port

This one's less common but I've hit it. A loose or damaged Ethernet cable plugged into the WAN port can trigger link flaps. If the router sees the WAN link drop and come back fast enough, it can panic and reboot. Especially on routers running PPPoE — the connection drops, the PPP session dies, and the router doesn't recover gracefully. Try a different cable. Also inspect the router's Ethernet port. Bent pins or debris inside can cause intermittent shorts.

Less Common Variations

Firmware Bug (but it's not)

Stock firmware on consumer routers is buggy. But a firmware bug that causes periodic reboots usually shows up after an update. If you just updated and now it reboots, roll back to the previous version. But in my experience, people blame firmware when the real issue is hardware. Don't flash a third-party firmware hoping it'll fix heat or PSU problems — it won't. OpenWrt or DD-WRT might be more stable, but they'll still crash if the hardware is failing.

Overloaded Power Strip or UPS

If your router shares a power strip with a space heater, a laser printer, or a gaming PC, the voltage can fluctuate when those devices kick in. A UPS with voltage regulation (line-interactive) can smooth that out. I've seen a router reboot every time a fridge compressor started on the same circuit. Put the router on a different outlet to test.

Wi-Fi Interference (rare for reboots)

Wi-Fi interference doesn't cause reboots — it causes disconnects. Users often confuse "my Wi-Fi dropped" with "the router rebooted." If your Wi-Fi drops but you can still ping the router's LAN IP, it's not a reboot. If you lose all connectivity for 30 seconds and the router's uptime resets, it's a reboot. Check uptime in the admin panel after it happens. If uptime is zero, it rebooted. If not, you've got a Wi-Fi problem, not a router reboot problem.

What About Factory Reset & Firmware Update?

Do them last. Here's why: a factory reset clears temporary corrupt config files. That can fix a router that's crashing because of a bad setting (like a wrong DHCP pool or a bad QoS rule). But if the router's hardware is fine, a factory reset won't help. Same for firmware updates — they fix security holes and add features, but they don't fix a 90°C CPU or a dying PSU. My rule: do a factory reset only after you've verified the hardware isn't the issue. And save your config first. You'll thank me.

Prevention: Keep It Alive

• Give it air. Don't stack books on top of it. Don't hide it in a closed cabinet. If your router sits on a shelf, make sure there's 2-3 inches of clearance on top and sides.
• Replace the PSU every 3 years. They're cheap. A $8 brick is cheaper than a $100 router. Mark your calendar.
• Use a small USB fan if your router runs hot. You can buy a $5 USB fan on any e-commerce site. Stick it on top blowing down. It looks ugly but works.
• Set a weekly reboot. Most routers have a built-in scheduler in the admin panel. Set it to reboot at 4 AM once a week. That clears memory leaks and keeps uptime clocks accurate. It also prevents the 'creeping crash' where the router gets worse over time.

That's it. Next time your router reboots, check the heat first. Then swap the brick. Then check the cable. You'll solve it before you finish your coffee.