High buffer bloat and erratic internet performance when under heavy load on 2.5GbE Ethernet using Realtek technology
High buffer bloat and erratic internet performance when under heavy load on 2.5GbE Ethernet using Realtek technology
Hey there, so I encountered a strange problem or maybe it was meant to happen. My cable company gave me a new router for my internet (AVM Fritzbox, German brand) that supports 2.5GbE LAN. I was thrilled, got a Realtek 8125 PCIe NIC, and everything seemed perfect – full 1500Mbit downloads and 100upload speeds. But sometimes I experience internet timeouts. During normal use like browsing or watching YouTube, it’s fine. However, when I play games such as Minecraft or World of Warcraft, I get disconnected from the servers. That’s when I realized something was wrong.
I checked some forums and sites like Waveform and Fast.com, and under heavy load I saw high latency and bufferbloat – around 12-13ms when idle and 130-140ms when under stress. At first I thought it was just the router or ISP issue, but then I connected my LAN directly to the mainboard’s onboard NIC (1GbE Realtek 8111H). The problem disappeared completely, and my latency dropped to 20-23ms. I tried forcing the LAN port to 1GbE without changes, updated drivers, even used the latest Realtek versions, but nothing fixed it.
Is the NIC faulty, or is this just how a 2.5GbE device behaves? I’m using a MSI MPG B550 Gaming Plus with a Ryzen 7 5700X and two NVMe drives – one in the top slot for CPU and one in the bottom for the chipset. The PCIe NIC is in the very bottom slot, which is auto-disabled by the chipset for NVMe. I’m not sure if this setup is affected.
Any tips or advice would be greatly appreciated!
Your LAN card in the x1 slot with B550 chipset lanes rated for Gen3 can only deliver 1GB per second. This means it won't work properly, and you might be experiencing drops. You could revert to using the board network to fix the issue without any loss of data.
The 1GbE mainboard onboard NIC works perfectly without any latency or bufferbloat problems. The 2.5GbE setup uses a single card, and the speeds were solid, though under heavy load the 1x connection might cause some delays and mini timeouts.
120ms isn't excessive; it's not like the games will consume all bandwidth like buffer tests suggest
A common method to reduce bufferbloat involves restricting your bandwidth. This can occur when you connect a 1Gbps LAN while your internet connection runs at 1.5Gbps. Another approach to lessen bufferbloat, apart from controlling speeds (such as with NetLimiter or router configurations), is to opt for a router that supports effective SQM (Smart Queue Management).
i completely understand, but these changes are clear when playing, especially in titles like mw3 and League. The spikes and load latency show up even when the system isn’t fully loaded. That’s why i prioritized the mainboard and 1gbe data—it stays stable around 23ms, unlike the over 130ms with the 2.5gbe NIC, suggesting something else is affecting performance.