Broadcom Netxtreme Gigabit Ethernet Only 100mbps

[Vicki Patolot]

Interestingthing to note, even Windows 10 running in BootCamp failed to connect faster than 100Mbps... but only AFTER updating to macOS High Sierra. It never failed to connect at 1Gbps before the macOS update.

I have a Windows 10 PC right next to this, and it works at 1Gbps no problems. The USB ethernet connects at 1Gbps no problem. I swapped the ethernet cords just in-case. The iMac still connects at 100Mbps and the Windows still connects at 1Gbps both internally and using USB.

I had this exact issue with my MBP mid 2015. Ethernet connection via Apple's thunderbolt adapter would only connect at 100Mbs. bringing my internet speeds to a miserable 80Mbs when I get 275Mbs on my 5G wifi connection. If I would switch the adapter hardware settings to manual and set it to 1000baseT it wouldn't even connect. After having my ISP come here and look at my router, all checked out well with them. So no issues with the router. Now I call Apple and get to top level tech and we try all sorts of things and nothing is helping.

What I noticed while waiting on hold, I pulled out the ethernet cable from the adapter and noticed that one of the gold pins in the adapter was slightly bent down (for me it was the 4th pin from the left). It wasn't bent very much but I could see a difference from the other pins. So I grabbed a sewing needle and was able to gently get the needle under the one pins and carefully bent it back into place and BOOM! It worked at 1000baseT again.

In short, check the pins in your adapter see if any of them look out of place even just a little from the other pins. Try to bend them back with a needle but be careful they can break very easily. If it breaks, you will have to purchase another adapter.

This more than likely happened by being thrown into my backpack with other adapters and pens etc. Im guessing the adapter and a pen got into a fight and the adapter survived with minor injuries this time. I will keep them separated now on since they can't get along together.

Therefore if your cable is/was CAT3 this would at best cause intermittent problems and possibly always just 100Base-T, if one of the four extra wires became disconnected or was loose this would also cause a similar situation.

These settings were figured out through trial and error on all the permutations essentially. The only thing that I found affected speeds were the Speed (must be 1000baseT) and the MTU it needed to be set to a number approx 3000 or higher. I'm not a network engineer so I don't know the problems i'm giving myself here by upping the MTU, so perhaps I'll have to change that back later, but as of right now everything is working perfectly.

Similar to others, the hardware seems to be fixed at 100. Despite others, however, manual configuration doesn't seem to help. I've verified my cable; its the same one I've been using for months at a gigabit speeds before this update. I've also tried some of the reset options but to no avail.

It's so frustrating that this change happened both in Mac and Windows immediately after updating to High Sierra. There had to be some kind of firmware patch(nerf) that's not listed in the update. It's ridiculous that even the USB gigabit ethernet has the 100Mbps cap.

You said that you swapped the cables with a Windows machine and even installed a USB-Ethernet adapter. When you did this did you keep the same switch/router port? Have you already tried to use physically another port on your switch/router?

After trying a thunderbolt gigabit ethernet adapter, I have full 1000Mbps speeds again. I can only assume there was some kind of firmware mess-up with the OS update. At least that won't affect 3rd party hardware.

Ethernet hardware is rated in megabits per second (Mbps), and the true theoretical maximum that you will experience is megabits divided by 8-bits per byte, or 125 Megabytes (MB) per second on a 1GigE interface, with CAT5E LAN cable. Due to network collisions, and other protocol traffic on your LAN, you will be lucky to achieve 100MB/s traffic on your local LAN. Less if your LAN traffic is passing through older 100BaseT switches.

The fiber speed to your location from the ISP has no bearing on your real world internal LAN speed per the first paragraph's limitations. That 125MB/s is the gas pedal all the way down, and there is no more.

I got similar issue, my iMac mid 2017 shows cable unplugged. However, when change hardware setting to automatic, it's connected but in 10baseT/Full duplex only. Other setting will be disconnected with cable unplugged message. After SMC/NVRAM, reinstall o/s, install older version o/s on external hard disk still in vain. Contacted Apple support online also no help at all. So decided to use USB-C to Giga Ethernet instead of built-in network port.

The problem is that when I share a folder from the guest to the network I can only access that folder att 10MB/s. That is, somewhere along the line my gigabit network is being choked down to a measly 100Mbit. I am not using a legacy connection.

Verify that you're not using any of the "Legacy NICs" in your Virtual Machines? These are limited to 100mbps. This may be causing the Virtual Network (bound to the physical NIC) to negotiate the lower speed.

Other things to do:- Update NIC drivers- Force 1gbps operation in Device Manager- Replace the patch lead connecting the problem NIC- check cable. Two threads above had a similar problem solved by replacing a cable.

I checked the link status (Get-Netadapter select interfaceDescription, Name, Linkspeed) on Powershell and found it running on 100Mbps. Changed the speed settings of the port on my network switch where the server is connected to from Auto and forced it to run on speed 1000. This solved my problem. Check if this helps.

I tried using the Dell support Chat today only to be thoroughly disappointed. They remote connected to my PC to verify the latest driver was installed and then said I could call a pay for support number to continue trouble shooting it. The PC is new. This is a problem from the manufacturer. Why would I pay to fix something that was broke from the beginning?

As a follow up to my earlier reply, I have determined that you can not force a Broadcom device to 1000MB. It will only connect at this speed using the Auto setting. This doesn't solve your problem but does explain why you can't find 1000MB speed as a forced setting.

You DO NOT need to use Cat6 for gigabit traffic period. A good Cat5e cable is sufficient and was used for a long time with gigabit before Cat6 came around. I've even seen gigabit work over short runs of Cat5.

b) ability/quality of the hardware at each end of the cable. I'm going from the Broadcom gigabit adapter in my PC to a Netgear prosafe Gbit switch. I could have plugged into my router which also has a Gb switch built in and perhaps got a different result.

I tried turning off the power management on the broadcom adapter and it made no difference. I'm running Windows 10 on an HP system so again you may have different results on a Dell box with different drivers perhaps.

I started tracing it from a port on my router to my laptop using a spare cable. Then, using the same port from router to basement and connect the cable to my laptop ensuring the cable is good. Once I got 1Gbps, i connect it the cable to switch 1. Then, using another cable from switch 1 to my laptop. All good at this point. I have another long Cat5e that connects between switch 1 to the other end of the basement where switch 2 is, the length is only 74 feet. The cable that connects between two switches was getting 1Gbps. From switch 2 port to my laptop was 1Gbps as well but not my desktop. I made sure my i'm connected to the 1Gbps NIC on my desktop and turned off power management but no dice. I didn't have a cable long enough so i daisy chained two Cat5e to my desktop and i was able to get 1Gbps.

half of what you said is good , however the cat5 vs cat6 thing you just wrote is completely false , I run cat5 gigabit just fine across my entire network . I have a certifier with results if you would like to see them . Cat6 , i.e. plastic piece in between pairs doesn't make a difference , cat6a with a higher gauge is capable of 10gps in short ( 10M) runs . but your cat5 and cat6 both are gigabit .

If you had a cable with exposed wire on the end on one of your devices this is what would cause that , but i see 103 MB a second on average over cat5 ( net is gigabit too in my case ) and DO NOT have a single cat6 anywhere in household or rack.

My problem is that my ethernet port (aka wired connection) is not available in Windows' Control Panel > Network & Internet > Network Connections. Only Bluetooth and Wireless are available. When I try to set up a connection, the only options are wireless and Broadband (PPPoE).

First of all, connect the adapter and reboot. In many cases, it will solve the problem. You need to reboot because the adapter is not hot-pluggable. For the same reason, if you remove and re-insert the adapter, it won't work until you reboot.

Google "broadcom driver windows netxtreme". Select the netxtreme I Desktop/Mobile driver. Install via device manager (select location where you unzipped driver). Note, the PCI ID for this device 14e4:1682 is not listed in Broadcom's web page list of supported IDs. However the driver's .inf does include the requisite matching for the new device ID.

Given the correct answer from iskra, here is a workaround I finally came to: set up Parallels Desktop (yes, it's not free) and use Thunderbolt for Bootcamp when Windows is run under Parallels. As long as network connection is set up in Parallels as Shared, effectively it makes Thunderbolt adapter hot-unpluggable for Bootcamp even within a single boot session. Parallels gives only a fraction of memory (normally not more than a half or 2GB) and only part of CPU power, but in some scenarios that's I can live with.

3a8082e126