Z-Wave Range Troubleshooting: Fixing Offline Locks

Executive Summary

Z-Wave does not work like Wi-Fi. It is a Mesh Network. If your hub is in the office and your lock is at the front door, the signal might need to "hop" through a light switch or a plug to get there.

If your lock is "Offline" or drains batteries in 2 weeks, your Mesh is weak.

The "4-Hop" Limit

Z-Wave messages can only jump 4 times.

• Hub -> Repeater 1 -> Repeater 2 -> Repeater 3 -> Lock.
• If the distance is too great, or if you have a concrete wall, the signal dies.

Troubleshooting Steps

1. Run a "Network Heal"

Z-Wave devices memorize their neighbors. If you move the hub, they get confused.

• Fix: Go to your Hub settings (SmartThings/Hubitat) and click "Repair Z-Wave Network" (or "Heal").
• What it does: Forces every device to say "Hello" to its neighbors and rebuild the map.

2. The "Repeater" Solution

Battery devices (Locks, Sensors) DO NOT repeat signals. They sleep to save power. You need Mains Powered devices to act as repeaters:

• Light Switches (Jasco/GE Enbrighten).
• Plugs (Minoston/Aeotec).
• Dedicated Range Extenders (Aeotec Range Extender 7).

Placement Rule: Place the repeater halfway between the hub and the lock. Do not put it right next to the lock (the signal is already dead by then).

3. Interference Assessment

Z-Wave operates at 908.4 MHz (US).

• Good: It doesn't fight with Wi-Fi (2.4 GHz).
• Bad: It fights with Baby Monitors and older Cordless Phones.
• Metal Doors: A metal door acts as a Faraday Cage. If your hub is behind the open door, and you close it, the signal is cut.

Battery Drain = Weak Signal

If a lock has a weak connection, it will scream. It tries to send the status update ("I locked!") at 100% power, fails, retries, fails, and retries again.

• Symptom: Batteries die in 2 weeks instead of 6 months.
• Fix: Add a repeater within 10 feet of the lock.

Related Tools

• Protocol Specs: Comparing Z-Wave to Zigbee range.
• Battery Life Calculator: Estimate impact of signal strength.