Can't get over 100MBPS on B450M Pro4

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   I bought this pre-built PC that came with a B450M Pro4 motherboard and even though in the specs page it says PCIE x1 Gigabit LAN 10/100/1000 Mb/s, I can't seem to get over 100MBPS on an Ethernet connection.

I'm positive it isn't the cable (it can handle the speed) or the modem (I'm getting 400MBPS+ on Wifi).

I've tried downloading the Realtek Lan driver ver:10050_07122021 and installing it but once I check the Ethernet stats (Win + R, ncpa.cpl) it still shows 100MBPS speed.

Not sure if it's just impossible to increase the ethernet port speed on the motherboard or I clearly don't know what I'm doing, or maybe both. 

Any help will be greatly appreciated! 

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MNA377 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 27 May 2022 Status: Offline Points: 20	Post Options Post Reply Quote MNA377 Report Post Thanks(0) Quote Reply Topic: Can't get over 100MBPS on B450M Pro4 Posted: 27 May 2022 at 8:03am
	I bought this pre-built PC that came with a B450M Pro4 motherboard and even though in the specs page it says PCIE x1 Gigabit LAN 10/100/1000 Mb/s, I can't seem to get over 100MBPS on an Ethernet connection. I'm positive it isn't the cable (it can handle the speed) or the modem (I'm getting 400MBPS+ on Wifi). I've tried downloading the Realtek Lan driver ver:10050_07122021 and installing it but once I check the Ethernet stats (Win + R, ncpa.cpl) it still shows 100MBPS speed. Not sure if it's just impossible to increase the ethernet port speed on the motherboard or I clearly don't know what I'm doing, or maybe both. Any help will be greatly appreciated!

threadzipper1957 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 05 Mar 2022 Status: Offline Points: 9365	Post Options Post Reply Quote threadzipper1957 Report Post Thanks(0) Quote Reply Posted: 13 Jul 2022 at 8:54pm
	Dear MNA377, When the system is switched on, your modem and LAN chip negotiate the protocol, and speed. Sometimes this is a compatibility issue between those 2, and a firmware update for the modem is required, this sometimes happens with Fritzbox. Look at the online manual, becasue the lights on the LAN port, also show the selected speed. You can try to set it to a fixed speed, or try half duplex of full duplex. If possible put a gigabit switch in between
	Kind Regards

threadzipper1957 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 05 Mar 2022 Status: Offline Points: 9365	Post Options Post Reply Quote threadzipper1957 Report Post Thanks(0) Quote Reply Posted: 13 Jul 2022 at 8:57pm
	Or try to make a bootable USB stick with Rufus, and create a USB stick with Ubuntu. Start the system, press f11, and select the USB stick, to boot from. You can run Ubuntu from the USB stick without installing. If the speed is the same, it is hardware related, if not, software related
	Kind Regards

Ricardo_63 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Sep 2025 Status: Offline Points: 30	Post Options Post Reply Quote Ricardo_63 Report Post Thanks(0) Quote Reply Posted: 30 Sep 2025 at 8:34pm
	Hi, have the same issue here and I sure it becomes from UEFI issue. In case by modifying Ethernet interface parameters to achieving a speed greater than 100MB, after power off and on it return to 100 MB LAN speed.

neolz75 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 20 Apr 2025 Status: Offline Points: 470	Post Options Post Reply Quote neolz75 Report Post Thanks(0) Quote Reply Posted: 8 hours 18 minutes ago at 1:43pm
	could be a low quality faulty ethernet cable, change cable and recheck or use the cable on another system if it shows at connection speed at 1Gbps.

Ricardo_63 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Sep 2025 Status: Offline Points: 30	Post Options Post Reply Quote Ricardo_63 Report Post Thanks(0) Quote Reply Posted: 2 hours 5 minutes ago at 7:56pm
	Is not a cable issue, clearly is driver issue. Windows assign and use a default driver, motherboards (as ASRock) Network Interface Controllers (NICs) and Communications Network ICs support speeds of 100 Mbps, 1 Gbps, and 2.5/5 Gbps. In case of 5G Gigabit Ethernet it needs GbE Family Controller Driver, thus it must check on Windows -> Device Manager -> network adapter -> advance properties, if loaded 5G driver parameters and GigaBit Lite must be enable, otherwise network interface it will be limited to Fast Ethernet (10/100 Mbps).