LAN Sync
Run HM Praxis on the front desk laptop, the doctor's iPad, and the back-office workstation - and have every change visible everywhere within seconds. All of it on your own local network.
LAN sync is available on the Pro tier. The Trial and Basic tiers are limited to a single device.
Setting Up Sync
Confirm Both Devices Are on the Same LAN
HM Praxis discovers peers by sending a small UDP broadcast on the local network. Both devices must be on the same Wi-Fi or Ethernet network (the same subnet), and any local firewall must allow HM Praxis to send and receive that broadcast.
Sync is purely peer-to-peer over your local network. There is no relay server. If your devices cannot see each other on the LAN, sync cannot happen.
Open Sync Settings on the Primary Device
Go to Settings > Sync. The primary device is whichever one currently has the database you want to share.
Enable Sync
Toggle Enable LAN sync on. HM Praxis begins broadcasting a small UDP announcement on the network every few seconds so other instances can find this device.
On the Second Device, Discover Peers
On the second device, open Settings > Sync. After enabling sync, the discovered peers list populates with any HM Praxis instances broadcasting on the LAN. Each device listens for the others' UDP broadcasts and builds the peer list automatically.
Perform the Initial Database Copy
On the second device, choose the primary peer and click Copy Database from Peer. This is a one-time bulk transfer to bring the second device up to the current state.
Bandwidth and database size determine how long. After the initial copy, only incremental changes flow between devices.
Verify Live Updates
Create or edit a patient on one device. Within a few seconds the change should appear on the other. If it does not, check that both devices still show "Connected" in their sync indicator.
How Sync Works
1. Discovery via UDP broadcast
Each device with sync enabled broadcasts a small UDP announcement on the LAN every few seconds. Other devices listen for those broadcasts and build a list of available peers automatically. Only devices in the same organization are added to the list.
2. Connection over WebSocket
Once peers have discovered each other, they open a WebSocket connection between devices to exchange data. Discovery (UDP broadcast) finds the peers; the WebSocket connection does the actual syncing.
3. Initial database copy
The new device pulls the full database from a peer in one transfer. This is a one-time operation per device.
4. Incremental changelog
After the initial copy, each change (create, update, delete) is recorded in a local changelog and pushed to connected peers. The peers apply the change to their own database.
5. Offline-tolerant
If a device drops off the network, it keeps working. Pending changes queue locally and sync up when the device reconnects.
What Syncs Across Devices
Practically every record type in HM Praxis is synced:
- Patients and their medical records
- Appointments, planned and used materials
- Prescriptions and their items
- Inventory items, categories, and stock changes
- Services, service categories, and material links
- Invoices, invoice items, and payments
- Treatment plans, milestones, and sessions
- Staff records
- Uploaded documents
- Branding and organization settings
Conflict Resolution
When two devices edit the same record while disconnected, HM Praxis applies a last-writer-wins policy based on the change timestamp. The rejected change is kept in the changelog so you can inspect what was overwritten.
- Most concurrent edits are on different records and never conflict
- For the same record, the most recent edit wins
- Delete-vs-edit conflicts resolve in favor of the delete
- The sync changelog keeps a trace for audit and debugging
Privacy and Encryption
Sync traffic stays on your LAN. Patient data does not leave your network during sync - it is never uploaded to rb-devops.com servers.
Because sync is LAN-only and trust is implicit, only enable it on networks you control. Avoid running sync on shared coffee-shop or airport Wi-Fi.
Sync Troubleshooting
- No peers visible: confirm both devices are on the same LAN and subnet, and that the local firewall allows HM Praxis to send and receive UDP broadcast
- Same network but still no peers: some Wi-Fi networks turn on client isolation (also called AP isolation), which blocks devices from seeing each other and drops broadcast traffic. Guest networks often have this on. Use a network you control with isolation disabled
- Initial copy fails: verify the primary device has not gone to sleep mid-transfer
- Changes do not propagate: confirm the sync indicator shows "Connected" on both ends
- One device is far behind: try toggling sync off and on to force a fresh reconnect
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