Two computers connected to the same network but running at varying speeds.
Two computers connected to the same network but running at varying speeds.
Hey everyone, I'm working through this network issue and trying to clarify what happened. I've outlined the scenario and the solutions I've attempted so far. I have two Windows 10 machines connected via Cat5e to my router, but one consistently outperforms the other. They're located about four feet apart in the same room. I've already tried several basic fixes—swapped cables, tested different ports on the router, even changed the Ethernet port on my gaming PC. I also restarted both devices and used various Windows versions with autotuning enabled. The server PC runs an i7 6700K with an ASRock Z170A board and delivers a stable 950 Mbps down and 40 Mbps up. My gaming PC uses an R9 3900X and an ASUS TUF X570-Plus, which shows erratic download speeds (150-500 Mbps) but maintains a steady upload. Ping remains consistent between the two. I've also tried different Ethernet cables and ports, and even ran a speed test on a Linux VM on my gaming PC. I ran Malwarebytes just to rule out malware, disconnected everything except the gaming PC, and reset the router settings. The only thing that worked was changing the LAN IP address and applying networking fixes. My router doesn’t appear to have QoS enabled—it’s a Spectrum SAX1V1S model. I’ve checked forums and YouTube advice, but most suggestions don’t seem to fit my setup. It seems like this is more about software or configuration than hardware. Any tips would be really helpful!
Consider moving the large file between the machines via the router using network cables connected to the router. If you achieve gigabit speeds, the issue might be hardware-related (faulty drivers, bad network card) or software not running for trusted local IPs. A firewall or antivirus could be filtering traffic and blocking the transfer. Check the advanced settings of your network card through Device Manager and turn off any power-saving features just in case the cable quality is low. Also, look into the jumbo frames setting—if it's enabled at an unsupported value, the router might reject it. Try booting from a Linux live USB to test if the speed improves, which could indicate a driver or Windows issue.
File transfer works without any issues, which gives me strong confidence it’s not hardware-related. I checked both the firewall settings and looked for potential causes, but nothing came up. The problem disappears when I start the system in Linux through a VM, where it functions perfectly. Safe mode with networking also resolves the issue.