How to Fix Slow Internet on One Computer When Others Are Fine

Published 2026-10-14 · Luxurious Computers Repair

Your internet works fine on your phone, tablet, and other computers, but one specific computer is painfully slow. Pages take forever to load, downloads are sluggish, and streaming buffers constantly — but only on this one machine. When the internet is slow on a single computer while the rest of the network performs normally, the problem is something specific to that computer: the network adapter, its drivers, its software configuration, or something consuming bandwidth on that machine alone.

Identify the bottleneck

• Run a speed test on the slow computer and immediately run the same test on another device connected to the same network. If the other device gets full speed (matching your ISP plan) while the slow computer gets significantly less, the problem is confirmed as computer-specific
• Check whether the slow computer is connected via WiFi or Ethernet. If it is on WiFi while the fast devices are on Ethernet (or closer to the router), the speed difference may be expected. Test the slow computer on Ethernet to isolate whether the issue is WiFi-related
• Note whether the slowness is constant or intermittent. If speed drops at specific times, a scheduled task (backup software, cloud sync, Windows Update) may be consuming bandwidth periodically

Check for background bandwidth usage

• Open Task Manager (Ctrl plus Shift plus Escape) and click the Network column header to sort processes by network usage. Look for any process consuming significant bandwidth. Common culprits include cloud sync services (OneDrive, Dropbox, Google Drive uploading files), game launchers (Steam, Epic downloading updates), Windows Update, and backup software
• If OneDrive or another sync service is uploading a large number of files, it can saturate your upload bandwidth, which slows down all internet activity including downloads. Most sync services have a setting to limit upload speed — reduce it to leave bandwidth for other activities
• Check for multiple browser tabs with streaming video, auto-playing media, or heavy web applications running in the background. A single tab streaming 4K video uses 15 to 25 Mbps, which can noticeably slow a connection under 100 Mbps

Scan for malware

• Malware on the slow computer can consume bandwidth by communicating with command servers, exfiltrating data, mining cryptocurrency, or participating in distributed attacks. This would only affect the infected machine, which is consistent with one computer being slow while others are fine
• Run a full scan with Windows Defender: open Windows Security, Virus and Threat Protection, Scan Options, select Full Scan. Also run a scan with Malwarebytes or another second-opinion scanner to catch threats the primary scanner may miss
• Check Task Manager for unfamiliar processes, especially those with high network or CPU usage. Research suspicious process names before ending them

Reset the network configuration

• Corrupted TCP/IP settings, a stale DNS cache, or a misconfigured proxy can slow internet on one computer. Open Command Prompt as Administrator and run these commands: netsh winsock reset, then netsh int ip reset, then ipconfig /flushdns, then ipconfig /release, then ipconfig /renew. Restart after running all commands
• Also check if a proxy server is configured. Open Settings, Network and Internet, Proxy. If Use a Proxy Server is enabled and you did not set it up, disable it. Malware sometimes configures a proxy to intercept traffic, which adds latency and slows browsing

Change the DNS server

• If the computer is using a slow DNS server, every new website connection starts with a delay while the name is resolved. Other devices may be using different DNS settings. Open your network adapter settings and change DNS to a faster provider like Cloudflare (1.1.1.1 and 1.0.0.1) or Google (8.8.8.8 and 8.8.4.4)
• After changing DNS, flush the cache with ipconfig /flushdns in Command Prompt. Test browsing speed — if pages start loading faster but download speeds remain the same, DNS was the bottleneck for browsing but not for throughput

Update or reinstall the network driver

• An outdated, corrupted, or misconfigured network driver can limit the adapter to lower speeds or cause packet loss that degrades performance. Open Device Manager, expand Network Adapters, right-click the WiFi or Ethernet adapter, and select Update Driver
• If updating does not help, uninstall the driver completely (check Remove Driver Software) and restart. Windows installs a fresh driver on reboot. Then download the latest driver from the laptop or adapter manufacturer website for optimal performance
• Check the adapter link speed: open Device Manager, double-click the network adapter, go to the Advanced tab, and look for Speed and Duplex. Ensure it is set to Auto-Negotiation, not forced to a lower speed like 100 Mbps half-duplex on a gigabit connection

Disable bandwidth-limiting features

• Some network adapters have power-saving features that reduce performance. In Device Manager, open the network adapter properties, go to the Power Management tab, and uncheck Allow the Computer to Turn Off This Device to Save Power. On laptops, the WiFi adapter may reduce power in battery mode, which limits speed
• Check if Windows has a bandwidth reservation policy. Open the Group Policy Editor (gpedit.msc on Pro editions), navigate to Computer Configuration, Administrative Templates, Network, QoS Packet Scheduler, and check Limit Reservable Bandwidth. If it is enabled with a high percentage, reduce it or disable it
• Some antivirus and security software includes a network monitoring feature that inspects all traffic. This adds overhead and can slow speeds. Check your security software settings for network scanning or web protection options and test with them temporarily disabled

Check the WiFi adapter specifically

• If the slow computer connects via WiFi, the WiFi adapter may be limited by its hardware capability. An older adapter supporting only WiFi 4 (802.11n) maxes out at 150 to 300 Mbps theoretical, which is 50 to 100 Mbps real-world. Other devices with WiFi 5 or WiFi 6 adapters get faster speeds on the same network
• Check the adapter specification in Device Manager. The adapter name usually indicates the standard (AC for WiFi 5, AX for WiFi 6). If the adapter is old, a USB WiFi adapter upgrade can provide a significant speed boost
• WiFi signal strength matters. If the slow computer is farther from the router or behind more walls than other devices, it gets a weaker signal and slower speeds. Check the WiFi signal strength in Settings, Network and Internet, WiFi — one or two bars indicates a weak connection

Check for VPN or network software

• A VPN running on one computer routes all traffic through an encrypted tunnel to a remote server. This adds latency and often reduces speed, especially if the VPN server is geographically distant. Check if a VPN client is active in the system tray and disconnect it to test
• Network optimization software, bandwidth managers, or parental control software installed on the computer may be throttling speed. Check installed programs for any network management tools and disable or uninstall them

Need help with your computer internet speed?

If your internet is slow on one computer and the troubleshooting steps above have not resolved the issue, LuxuriousComputers Repair can diagnose network adapter problems, remove speed-limiting software, update drivers, and optimize your network configuration for the fastest possible connection.