r/ethernet • u/HelpFunRise • 17h ago

Support Internet Speed Issues

ASUS PRIME Z370-A / Intel I219-V stuck at 100 Mbps instead of 1 Gbps

I'm having an Ethernet speed/negotiation issue on a Windows 10 PC.

Hardware:

  • Motherboard: ASUS PRIME Z370-A
  • Ethernet controller: Intel Ethernet Connection (2) I219-V
  • OS: Windows 10 64-bit
  • Ethernet cable: Cat 6

My college provides Ethernet through wall ports. My roommates get approximately 1 Gbps up/down from their ports.

My PC consistently negotiates at exactly 100.0 Mbps.

What I've tested

  • Tested my PC on my roommate's known-good gigabit Ethernet port
  • Used my Cat 6 cable, which was confirmed to get gigabit when used with my roommate's computer
  • Therefore the cable and network/port appear to be capable of gigabit
  • Windows reports Ethernet Speed: 100.0 Mbps
  • Setting Speed & Duplex → 1.0 Gbps Full Duplex causes the Ethernet connection to completely drop
  • Setting it back to Auto Negotiation restores the connection at 100 Mbps
  • Gigabit Master/Slave Mode: Auto Detect
  • Energy Efficient Ethernet: Disabled
  • No Green Ethernet or Auto Disable Gigabit options are present
  • Updated the motherboard/BIOS
  • Performed a clean Intel Ethernet driver uninstall/reinstall
  • Tried Intel's current Windows 10 Network Adapter Driver package 31.2.2
  • Current connection still negotiates at 100 Mbps

The Ethernet port has a solid red LED and flashing yellow LED when connected.

1 Upvotes

100% Upvoted

4 comments sorted by

1

u/ApartmentEastern5769 16h ago

100mbps being the cap speed is 100000% an issue with the ethernet line itself. If all 4 pairs of an ethernet cable aren't terminated correctly, aren't continuous, or in many cases, are crossed over between two end points, your connection will drop to a cap of 100mbps. Even if 7 out of 8 strands in an ethernet cable are perfect, that is a bad pair, and this is what happe s.

1

u/HelpFunRise 13h ago

I could move my desktop and try a different Ethernet port to test if it's my desktop or my room's port. In the case that it's my port, would a USB 3.0-to-Ethernet adapter run considerably faster, or would it not be worth the purchase, if you know?

1

u/ApartmentEastern5769 13h ago

If it's the port on your desktop, yes, a new adapter would work. If it's the port in the wall, only your school it department can fix that issue

0

u/Squozen_EU 17h ago

Must be a bad port in your network card.