Use safely: Follow these steps only for a router or network you own or are authorised to manage. Never send Router Portal a router password, Wi-Fi key, MAC address, serial number or private screenshot.
Evidence and scopeSOURCE-BACKED · CHECK DATE
Sources2 official references
ScopeModel/OS/network dependent
CredentialsNever universal
ReviewRecheck after UI changes
Quick answer: A link that negotiates at 100 Mbps can be limited by cable pairs, port capability, adapter settings, a wall jack or a damaged connector.
What this page covers
Check negotiated link speed first; an Internet speed test alone cannot identify the physical bottleneck.
Step-by-step workflow
- Read the negotiated link speed on the client or switch.
- Swap one cable and one known-good port.
- Compare the same device at another authorised port.
- Keep auto-negotiation unless the manufacturer documents another requirement.
Decision table
| Check | What it tells you | Safe next action |
|---|---|---|
| Link is 100 Mbps | Physical path or port may limit the link | Swap cable/port systematically |
| Link is 1 Gbps, Internet slow | WAN or service path is separate | Test gateway and ISP path |
| Only one wall jack fails | In-wall termination may be involved | Use a direct cable comparison |
Limits and verification
Do not force duplex or speed without documentation; mismatched settings can make the link less stable.
Official sources
- Microsoft — Essential network settings and tasks (Windows network fields and commands)
- CISA — Securing Home Network Devices (home-network safety guidance)
Related Router Portal guides
Router login troubleshooting · Subnet calculator
Editorial note: This pilot page is written for one distinct question. Firmware, operating-system menus, ISP policies and regional radio rules can change, so confirm the source and exact device before applying a setting.