Dolphin can’t connect to the server — how to fix it

Fastest fix

From a working front-desk PC, confirm Dolphin still opens. On the failing PC, ping the Dolphin server by name and by IP. If ping fails, fix network/DNS first. If ping works, reopen Dolphin and verify the server/host field still points at that same name — Windows updates and profile rebuilds often blank or revert it.

Is it just you or is it everyone?

One PC vs all clinical stations. If everyone is down, go to the Dolphin server (or VM): powered on, disk not full, SQL/Dolphin services running. If one PC is down, stay on that client’s path, hosts file, and stored server name.
Imaging vs Management. Note which product throws the error. Shared database host issues take both down; a bad local Imaging path can look like “can’t connect” while Management still works.
Can you browse to the server share? In File Explorer open \\SERVERNAME (your real Dolphin host). If Windows can’t reach the share, Dolphin won’t either — fix SMB/network before repairing the app.

Causes (most common first)

1 · Most common

Wrong or blank server name on the client

Check: On the Dolphin login/connection screen, confirm Server / Host matches a known-good workstation. Typical on-prem setups use a short hostname or FQDN — not “localhost” on a clinical PC.

Healthy: Same server value as working PCs; connection succeeds within a few seconds.

If not: Enter the correct host, save if prompted, relaunch. If the field won’t stick, launch Dolphin “as Administrator” once to write the setting, then test as the normal user.

DNS / name resolution after network change

Check: Command Prompt: ping DOLPHINSERVER then ping 192.168.x.x (your server IP). If IP works and name fails, DNS or hosts file is wrong. ipconfig /all — confirm DNS servers are the practice DCs/router you expect, not a random public DNS that can’t resolve internal names.

Healthy: Hostname resolves to the correct LAN IP; ping replies (if ICMP allowed).

If not: Set DNS back to internal servers, or add a temporary hosts entry only as a bridge while DNS is fixed properly. Flush DNS: ipconfig /flushdns.

SQL Server or Dolphin services stopped on the host

Check: On the server, open services.msc. Confirm SQL Server (instance name varies — often MSSQLSERVER or SQLEXPRESS) is Running. Start related Dolphin services if your install lists them. Check Event Viewer → Application for SQL startup errors (disk full is common).

Healthy: SQL Running; clients authenticate; recent patient records open.

If not: Start SQL; if it stops again immediately, free disk space on the data volume and check the SQL error log before restarting in a loop.

Firewall / SMB blocked after a security tool update

Check: From the client, Test-NetConnection or telnet to the SQL port your site uses (often 1433 for default instances — confirm with IT; named instances may differ). Confirm Windows Firewall on the server still allows the Dolphin/SQL rules on the Domain profile.

Healthy: Port reachable; Explorer can open the image share if Imaging uses one.

If not: Re-enable the documented firewall rules. Don’t turn the whole firewall off permanently to “make Dolphin work.”

Stop it happening again

Standardize the Dolphin server hostname in a one-page office IT sheet taped in the server closet and in your password vault.
Monitor disk space on the SQL data volume; alert before free space hits zero.
Keep SQL and Dolphin services set to Automatic; after Windows Server updates, verify services before clinical hours.
Clinical PCs should use internal DNS that can resolve the Dolphin host — not guest Wi‑Fi DNS.

When to escalate

Dolphin / Patterson support: Database attach errors, version mismatches after an upgrade, licensing that blocks connection.
Your IT partner: SQL won’t stay up, subnet/VPN routing, firewall design, VM host problems.
On-site ASAP: Suspected disk failure, RAID alerts, or server that won’t power on — don’t keep power-cycling a clicking drive.

If stations lose Dolphin after every network tweak, it’s usually DNS, SQL lifecycle, or firewall rules — that’s the kind of thing we set up properly for orthodontic practices. Free 15-minute look at it: 615.821.0000.

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