Technician helping fix an Acer computer that needs frequent restart

Steve H.

Reviewed for technical accuracy

Specialities: Windows 10/11 network troubleshooter fails, “troubleshooting couldn’t identify the problem,” Diagnostics Policy Service not running.

When network diagnostics won’t run — common causes and the safest checks (services, adapters, DNS, updates)

Technician avatar Technician
Hi! Let’s keep this safe and simple — no risky “reset everything” moves.

When the Windows network troubleshooter fails, it can look like a big mystery, but it’s often one of these:
1) A Windows diagnostic service isn’t running (the troubleshooter can’t do its job)
2) The desktop is connected, but DNS (website name lookup) is failing
3) A network adapter is confused after an update (Wi-Fi/Ethernet driver changes)
4) A VPN, proxy, or security setting is blocking the diagnostic test

Trust moment: I don’t want you changing advanced settings while you’re unsure. We’ll start with “observe first” checks.

First: what message do you see? For example, “Troubleshooting couldn’t identify the problem,” “Diagnostics Policy Service is not running,” or an error code?
Customer
It says the troubleshooter can’t fix it. Sometimes it says “The Diagnostic Policy Service is not running.” I’m older and this makes me nervous.
Technician avatar Technician
You’re not alone — that message is common, and it doesn’t mean your computer is “ruined.”

Quick, safe questions (no clicking yet):
• Is your desktop on Wi-Fi or Ethernet cable?
• Do you have any internet at all (some sites work, email works), or is it fully offline?
• Did this start after something changed — a Windows update, a new router, or a VPN app?
Customer
Ethernet cable. Some things work sometimes, but web pages fail a lot. It started after a Windows update. I ran the network troubleshooter because I thought it would explain it.
Technician avatar Technician
That helps. If it’s “some things work, some fail,” it can be DNS or a browser/app difference — not always the cable.

And if Windows says the diagnostic service isn’t running, the tool itself may be failing even if the network is the real issue.

Trust moment: I don’t want you installing “driver fixer” programs. We’ll stick to built-in, reversible checks.

When the problem happens, does your network icon show “Connected,” or does it switch to “No internet”?
Customer
It usually says connected, but pages spin and don’t load. Then the troubleshooter fails and gives that service message.
Technician avatar Technician
That “connected but pages won’t load” is a classic sign that the link is up, but something else is stuck (often DNS, proxy, or a security filter).

Let’s separate two issues:
A) The internet problem
B) The Windows diagnostic tool failing

Safe check question: do other devices in the same home (phone/tablet) have normal internet at the same time?
Customer
Yes, my phone works fine on Wi-Fi. It’s mostly this desktop acting strange.
Technician avatar Technician
Good — that points away from “the whole internet is down.”

The Diagnostic Policy Service message is important because Windows network diagnostics rely on it. If it’s stopped or disabled, the troubleshooter may fail even when the fix is simple.

Before we touch anything: is this a personal PC, or is it managed by work/school (sometimes settings are locked)?
Customer
Personal Windows 11 desktop. Nobody manages it. I just want a clear explanation of what’s safe to try.
Technician avatar Technician
Perfect. Here’s the simple explanation: the troubleshooter is like a “test kit.” If the test kit’s service is turned off, it can’t run the test — so it reports a failure that isn’t the same as the network problem.

Safest next checks (still gentle):
• Confirm whether you’re using any VPN or proxy (even accidentally).
• Note if the issue is worse after waking from sleep or right after startup.
• Check if Ethernet shows a steady link light on the PC/router port (no unplugging needed, just look).

When you ran diagnostics, did it ever mention proxy settings, DNS, or a “default gateway”?
Customer
It once said something about proxy settings. I don’t use a VPN. I didn’t change anything myself.
Technician avatar Technician
That’s a useful clue. A proxy setting can be turned on by software, or sometimes by accident, and it can make pages fail while Windows still shows “connected.”

Trust moment: we’ll avoid changing a bunch of items. If we touch anything, it’s one small, reversible setting at a time.

Another safe question: do you use a browser extension or security app that filters web traffic (ad blocker, antivirus web shield)?
Customer
I have antivirus, but it’s been there for years. The update was the only new thing.
Technician avatar Technician
That lines up with an “environment change” issue: Windows updates can refresh networking parts and sometimes leave diagnostics or adapters in a strange state.

A safe way to proceed is to gather two clear facts:
• Does the desktop fail on all browsers or only one?
• Does the problem happen on all websites or mostly “some” (bank/news/email)?

If only some sites fail, DNS or security filtering becomes more likely. If everything fails, adapter or proxy becomes more likely.
Customer
It’s mostly all sites when it happens. Then it comes back. The troubleshooter still doesn’t help, so I feel stuck.
Technician avatar Technician
That’s exactly why a simple explanation helps: the troubleshooter is failing, so it isn’t giving you the “why.”

The safest next step is to confirm whether Windows diagnostics are able to run at all (service running), and separately confirm whether your connection is dropping (adapter/driver) or the web lookup is failing (DNS/proxy).

If you open the chat, tell me: the exact wording of the error, whether Ethernet is direct to the router, and whether “proxy” is turned on in Windows settings. I’ll guide you through the lowest-risk check first.
Customer
Okay. I can do that. I just don’t want to make the internet worse.
Technician avatar Technician
You won’t — because we’re doing “safe checks” first, not random changes.

Summary of what we learned: your phone works, the desktop is inconsistent, and Windows diagnostics sometimes fail because the diagnostic service isn’t running. That can create a false “no answer” feeling.

Next safe move is to confirm the basics (no proxy/VPN, steady Ethernet link) and make sure Windows diagnostic services are enabled so the tool can actually report useful results. Then we decide what to adjust — only if needed.

Quick answer: safe first checks when Windows network troubleshooting fails

Accepted first checks for a desktop network troubleshooter that fails:
• Write down the exact message (service not running, proxy, DNS, gateway) — it changes what’s safe to check next.
• Confirm other devices have normal internet; if they do, focus on the desktop (adapter, DNS, proxy) instead of the router.
• Check whether a proxy or VPN is enabled (these can break browsing while Windows still shows “connected”).
• If the message mentions diagnostics services, verify Windows diagnostics are not disabled (the troubleshooter can fail even when the network issue is simple).
• Avoid “network reset” or uninstalling drivers until you’ve done the low-risk checks above.

Why the Windows network troubleshooter can fail (even on a real problem)

Network diagnostics depend on Windows services that collect information and run tests. If a service like the Diagnostic Policy Service is stopped or disabled, the tool may not run correctly and can report unhelpful results. That can make it feel like “nothing works,” even if the actual issue is a simple setting (proxy), a DNS hiccup, or an adapter problem after an update. Separating “the tool failed” from “the internet failed” makes the next step much safer.

What to check first: proxy settings, DNS symptoms, and adapter changes

Start with the easiest checks: confirm you are not using a proxy, confirm other devices work, and notice whether the desktop problem is constant or comes and goes. If the desktop shows “connected” but pages won’t load, DNS or proxy is more likely than the cable. If the connection drops after sleep or after updates, the network adapter driver becomes more suspicious. Make one change at a time only after you know which “bucket” your symptoms fit.

Network troubleshooter fails — simple, senior-friendly explanation

If the tool can’t run, it may not be telling you what’s actually wrong.

A failing troubleshooter doesn’t always mean a failing computer. Sometimes Windows diagnostics are disabled, so the test can’t complete. Other times the desktop is connected but web browsing fails due to proxy or DNS. The safest approach is to confirm what works (other devices, VPN/proxy off, steady Ethernet) and then use the error message to choose the next check carefully.

Disclaimer: This information is AI-generated and intended for general guidance only. Avoid unknown “network repair” utilities and change one setting at a time so it’s easy to undo. If the desktop is work-managed, some settings may be locked by policy.

What to check next

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FAQ

Why did Windows network troubleshooting stop working suddenly?

This can happen after a Windows update, a cleanup tool, or a settings change that disables diagnostic services. If Windows can’t run its diagnostic service, the tool may fail even if your internet issue is real. Write down the exact error message first. That message usually points to what’s blocked.

Did this happen after an update?

It often does. Updates can change network drivers, reset network settings, or adjust security rules. That can affect both your connection and the troubleshooting tool. If the timing matches an update, focus on safe checks like proxy/VPN and connection stability before deeper changes.

Is this a settings issue or hardware?

Many cases are settings (proxy, DNS, VPN, services). Hardware is more likely if Ethernet link lights drop, the cable is loose, or the adapter keeps disconnecting. If other devices work fine, it points toward the desktop’s adapter or settings. The goal is to separate “tool failed” from “network failed.”

Can this be checked safely at home?

Yes. You can safely confirm other devices work, check whether a proxy/VPN is enabled, and note whether the problem is constant or comes and goes. You can also read the exact Windows error message without changing anything. Those steps are low risk and help avoid random “fixes.”

Sources

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