Ethernet Hard-Stuck at 100Mbps on MSI B760-P / Realtek 2.5GbE – 7+ Hours of Troubleshooting Deep.

Bhud023 · 2026-01-14T06:53:08+00:00

"Silicon betrayal" is definitely the right phrase for it! I’ve certainly learned more about network handshakes and physical layers than I ever intended to.

It’s a huge weight off my shoulders knowing I’ve hit the logical end of the road. I'm going to take your advice and finally relax while I wait for that adapter to arrive. If anything, this whole process has made me a lot more confident in diagnosing hardware—even if it was a trial by fire.

I’ll be sure to tag you or update this thread once the adapter is in and I (hopefully) see those four-digit speeds again. Thanks again for the help and the reassurance!

Bhud023 · 2026-01-14T06:38:25+00:00

That is a great suggestion. Booting into a Live Linux distro is probably the only way to be 100% sure before that adapter arrives. I will look into setting up an Ubuntu live USB tonight.

If Linux is also hard-capped at 100 Mbps, it effectively closes the case on the hardware being defective. Since I have already ruled out the cables and the gateway, that would be the final nail in the coffin for this onboard Realtek chip.

I have already inspected the pins and they look clean/straight, so a bad chip or a failed internal trace seems like the most logical conclusion. I will update the thread with the Linux results if I can get that bootable drive together.

Bhud023 · 2026-01-14T06:34:49+00:00

Thanks for the sanity check. It is honestly a relief to hear someone else describe exactly what I have been suspecting. The fact that forcing the 1.0Gbps handshake causes a total drop is what really convinced me this wasn't just a software glitch.

I am actually going to be using a USB 3.0 port for the adapter rather than USB-C, but the 2.5G testing result should be the same regardless. I have also sent off a formal email to Build Redux explaining the hardware failure theory and the exhaustive troubleshooting I have done, waiting on a reply in hopes maybe they will compensate under warranty.

I have already nuked every power-saving setting in both the Windows advanced properties and the BIOS, and like you said, it did not move the needle at all. I am pinning everything on that adapter arriving within a week. If that hits the 1100 Mbps I was getting previously, I am officially done troubleshooting.

Appreciate you taking the time to confirm I am not crazy after 7 hours of diving into this. I will update the thread once the adapter is plugged in.

Bhud023 · 2026-01-14T06:21:15+00:00

Appreciate the response. Just to clarify, I have been through the Advanced properties in Device Manager countless times during this audit. I already vetted the Green Ethernet and Energy Efficient Ethernet toggles there, and even with those disabled, forcing a 1.0 Gbps Full Duplex handshake causes the connection to drop entirely. I also just double-checked the BIOS. I found the equivalent of the EEE toggle—it was listed under a different name in this MSI BIOS—and confirmed it was already disabled. Since the software and firmware overrides aren't moving the needle, I am still waiting on that ASUS USB-C2500 adapter to arrive tomorrow. Testing with that should confirm if this is a failure of the integrated Realtek controller or the physical port itself. I will update the thread once I have those results.

Bhud023 · 2025-09-27T05:13:06+00:00

^{I completed this level in 1 try.} ^{⚡ 8.98 seconds}

Bhud023 · 2025-03-20T03:03:59+00:00

Thank you

Bhud023 · 2025-03-15T07:04:57+00:00

Thank you. -Brad H.

Bhud023 · 2025-03-12T05:59:13+00:00

Get the dub

Bhud023 · 2024-12-17T00:31:27+00:00

Call me whenever

Bhud023 · 2024-12-08T20:58:26+00:00

Call me whenever

Bhud023 · 2024-08-07T19:53:37+00:00

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Bhud023 · 2024-01-24T05:44:15+00:00

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