I'm really frustrated right now. I've been troubleshooting my brand new PC build for over six hours, and I just can't seem to fix my internet speeds. My Ethernet connection is stuck at 100 Mb/s, and my Wi-Fi barely reaches 120 Mb/s. My other devices, like my laptop and phone, are getting 400-600+ on Wi-Fi and 650-700+ on Ethernet, all using the same cables and ports.
I've tried a ton of things:
- Used three different new Cat-6 cables
- Connected directly to the modem (Spectrum EN2251 DOCSIS 3.1)
- Power cycled the modem
- Updated and flashed the BIOS multiple times
- Fully cleared the CMOS
- Fresh installs of both Windows 11 and Pop!_OS
- Tested all Realtek drivers (default, MSI's latest, and older versions)
- Disabled settings like Green Ethernet and EEE
- Forced 1.0 Gbps Full Duplex, but still no change
- Tried different ports and devices, yet everything else works fine.
My build includes:
- AMD Ryzen 9 9900X3D
- MSI MAG X870E Tomahawk WiFi (Realtek RTL8125B 2.5Gb Ethernet, Qualcomm FastConnect 7800 Wi-Fi 7)
- 64GB G.Skill Trident Z5 Neo DDR5-6000
- Gigabyte RTX 5080 Aorus Master
The Realtek NIC won't negotiate beyond 100 Mb, and while the Wi-Fi is a little better, it caps out at around 110-120 Mb/s, which feels underwhelming for a new chip. I don't know if there's a hardware defect with the RTL8125B, a bad jack, or if it's a firmware issue. I just want to enjoy my setup! Any suggestions before I consider returning the motherboard?
5 Answers
Have you checked to see if your chipset drivers are updated? Also, if you have an MSI board, be careful with the Killer network software; it can mess things up.
It sounds like you might have a faulty NIC. If other devices can link at gigabit speeds using the same cables, that's a strong indication of an issue with your network card. It could be worth it to just grab a cheap PCIe NIC for around $30. It might save you the hassle of RMAing your whole motherboard. It's a quick fix that many people have had success with!
I noticed similar issues where my Windows settings showed a link speed of 100/100 when plugged into the motherboard, but when I used a dongle, it showed 1000/1000 and I got the speeds I needed. Might be worth exploring dongle options.
Make sure your NIC settings are set to 'Auto Negotiation' for the best speed. Also, check if it's configured to connect at 5GHz for Wi-Fi instead of limiting it to 2.4GHz. Also, inspect your Ethernet port for any damaged pins because even one bad pin can drop your speeds.
Using a USB-C to Ethernet dongle improved my speeds significantly, hitting over 600 Mbps.
If it keeps giving you trouble, consider swapping out the motherboard for a more reliable one. Just something basic like the Asrock B850 Riptide WiFi could do the trick without breaking the bank.
Totally agree. I had a similar problem until I got a 2.5 gig PCI card. Now I’m enjoying full speeds on my setup, no issues at all.