RDP Multi-Monitor Setup & Connecting to a Non-Domain (Workgroup) PC

Two things people hit with Remote Desktop (RDP): getting it to use all your monitors, and connecting to a PC that isn’t on a domain (a workgroup/standalone machine) where the username format trips them up. Here’s both.

Part A: Use all your monitors

There are three equivalent ways to turn on true multi-monitor:

1. GUI: in Remote Desktop Connection (mstsc), expand Show Options → Display and tick “Use all my monitors for the remote session.”
2. Command line: run mstsc /multimon.
3. .rdp file: add the line use multimon:i:1 (1 = on, 0 = off).

/multimon gives true multi-monitor — each local monitor maps to a separate display in the session, and mixed resolutions/layouts are fine.

Span vs. multimon

mstsc /span is different: it stretches the session across monitors as one big display. Span has rules — the monitors must be the same resolution and side-by-side (horizontal). For most setups /multimon is what you want; use /span only for a single stretched desktop.

Pick specific monitors (2 of 4, 3 of 4…)

You usually don’t want every screen — just some of them. RDP lets you choose, with two rules: use multimon:i:1 must be set, and the monitors you pick must be contiguous (a connected block, no gaps).

Find the IDs first: run mstsc /l — it lists each monitor with its ID (the primary is 0). Note which physical screen is which.

Then set selectedmonitors to that comma-separated list. Say you have four monitors 0,1,2,3 left-to-right:

use multimon:i:1
selectedmonitors:s:0,1          # leftmost 2 of 4
selectedmonitors:s:1,2,3        # right-hand 3 of 4
selectedmonitors:s:0,1,2,3      # all four

Contiguous means no skipping. With 0,1,2,3 in a row, 0,1 / 1,2 / 2,3 / 0,1,2 / 1,2,3 are all valid — but 0,2 (skips 1) and 0,3 are not. Pick screens that sit next to each other.

The remote PC must be a multimon-capable edition (Windows Pro/Enterprise/Education or Server), and RDP supports up to 16 monitors.

Edit the .rdp file by hand

The GUI checkboxes just write settings into a .rdp text file — and editing that file directly is the most reliable way to lock in multi-monitor and monitor-selection (the GUI has no box for “monitors 1,2,3”).

Get the file: open mstsc → Show Options → fill in the PC → Save As… to create a .rdp file (saving the default connection writes Default.rdp to your Documents folder). To edit one: right-click the .rdp file → Edit reopens it in the RDP client, or right-click → Open with → Notepad to edit the raw lines.

A typical file looks like this — the lines that matter here are at the top:

full address:s:OFFICE-PC
username:s:OFFICE-PC\admin
screen mode id:i:2
use multimon:i:1
selectedmonitors:s:1,2,3
authentication level:i:2
prompt for credentials:i:0

• full address:s: — the PC name or IP you’re connecting to.
• username:s: — note the COMPUTERNAME\user format (see Part B).
• screen mode id:i:2 — full screen (1 = windowed).
• use multimon:i:1 + selectedmonitors:s: — the multi-monitor pair from above.

Save the file, double-click it, and it connects with exactly those settings every time.

You can’t type a password into the .rdp file. There’s a password 51:b: field, but it’s encrypted to your Windows account (DPAPI) — a plaintext password won’t work, and a saved one only works for the user/PC that created it. Save credentials the supported way instead (next section).

Part B: Connect to a non-domain (workgroup) machine

A workgroup PC has no domain to authenticate against, so you sign in with its local account — and the username format matters.

1. Turn on Remote Desktop on the target PC: Settings → System → Remote Desktop → toggle on, and note the PC name shown. (Windows Home can’t host RDP — only connect from it. The host needs Pro/Enterprise/Education.)

2. Use the right credential format. When connecting, enter the username as one of these — not just the bare username (RDP may try to authenticate it against your own machine’s domain):

COMPUTERNAME\username      (e.g.  OFFICE-PC\admin)
.\username                 (the leading .\ means "this remote computer")

If the remote account signs in with a Microsoft account, use that email address and its password (you may need to have set a password/PIN on it first).

3. Reachability & firewall. Make sure you can reach the PC by name or IP on the network, that it’s powered on, and that TCP 3389 is allowed through its firewall (enabling Remote Desktop adds the rule automatically). On different subnets, connect by IP address.

Save the password (so it stops asking)

Since you can’t put the password in the .rdp file, use one of these — all store it in Windows Credential Manager, not the file:

1. The checkbox: in mstsc, after typing the username, tick “Allow me to save credentials” (or “Remember me” on the credential prompt). Windows saves it to Credential Manager for that PC.
2. Command line (cmdkey): pre-store it without connecting —

   cmdkey /generic:TERMSRV/OFFICE-PC /user:OFFICE-PC\admin /pass:YourPassword

   (Use the same TERMSRV/ prefix and the COMPUTERNAME\user format.)

The workgroup catch: by default Windows refuses to use saved credentials for a non-domain (workgroup) host — you’ll still get prompted even after saving. To allow it, enable a Credentials Delegation policy: gpedit.msc → Computer Configuration → Administrative Templates → System → Credentials Delegation → “Allow delegating saved credentials with NTLM-only server authentication” → Enabled → Show → add TERMSRV/OFFICE-PC (or TERMSRV/* for any host). After that, the saved password is actually used.

FAQ

The remote session only fills one screen. Multimon isn’t on, or you connected before enabling it — use mstsc /multimon (or tick “Use all my monitors”). Note /span won’t help if your monitors differ in resolution.

I set selectedmonitors but it ignores it / uses all screens. Two causes: you didn’t also set use multimon:i:1 (it’s required), or your list isn’t contiguous (e.g. 0,2). Run mstsc /l to confirm the IDs and pick adjacent ones.

“The logon attempt failed” on a workgroup PC. It’s the username format — prefix it with the remote computer name: PCNAME\user or .\user (Part B, step 2). Also confirm that local account actually has a password (blank-password accounts are blocked from RDP by default).

Connected but can’t save my password. That’s the workgroup default — enable the Credentials Delegation policy (see Save the password above), or store it with cmdkey /generic:TERMSRV/PCNAME /user:PCNAME\user /pass.

Sources: Microsoft Learn — mstsc command (/multimon, /span, /l), Microsoft Learn — Supported RDP properties (use multimon, selectedmonitors), Microsoft — How to use Remote Desktop, Microsoft Learn — Enable Remote Desktop on your PC