Experiencing a notable slowdown in the secondary router linked through a CAT6 LAN cable
Experiencing a notable slowdown in the secondary router linked through a CAT6 LAN cable
Hi Everyone, I just changed ISPs and now have a speed of 150 Mbps thanks to the router they gave me. But the WiFi doesn’t reach the second room, so I connected a 20-meter RJ45 Cat 6 cable to the WAN port in that room. I was using it before as my main router. Since it supports both 2.4 and 5 GHz bands, I thought I’d get the same speed there too on the 5 GHz band. However, after several tests over a few days, I consistently got only 92 Mbps, which is roughly a 40% drop. Is this typical? Are there any steps I can take to improve it? Also, why does this happen? P.S.: When I tried connecting the other end of the RJ45 cable (the one linked to the secondary router) to my laptop, I got full 150 Mbps—so the issue isn’t with that cable.
Your internet service provider is providing a router that supports speeds around 92mbps, which typically corresponds to older 'fast ethernet' standards capped at 100mbps. Unless the device arrived damaged or faulty, this is less likely. If you purchased it new, that scenario is improbable but not impossible.
There is a primary router and a secondary router. Primary router (The one provided by ISP) gives me 150 Mbps on speed test. So def not limited to 100 Mbps. The secondary router is the 1 I linked in initial post, which is again not limited to 100 Mbps. Also on connecting the cable directly to my laptop instead of the secondary router, I am getting 150 Mbps. Thus the dilemma. Yes the cable is brand new.
It's intriguing. I've confirmed the secondary router on Amazon includes gigabit ports, yet I'm still puzzled about the issue.
It operates on a 5GHz channel width. You should aim for 80MHz for optimal performance, though I’m not sure why 40MHz ended up in my tests—20MHz usually caps near around 90MHz. A narrower width gives stronger signals closer, but less data speed. Nearby APs support 20, 40, and 80 options at 5GHz. For the one above my office, it’s configured at 80MHz, which works well without needing long range. I can fine-tune it up or down to 300-400 MHz on a mid-2015 MacBook Pro.
Adjusted the frequency to 80 MHz and still didn’t get results. I think I’ve identified the issue. On the TP-Link Archer A6 page, Ethernet negotiation shows 100 Mbps full duplex, even though it’s a gigabit device. It isn’t using the standard cable or port from the main router; instead, connecting directly via RJ45 gives full 150 Mbps. Looks like a firmware glitch on TP-Link.
It isn't always the case that a poor cable works on one device but not another. Each network adapter handles minor cable issues differently based on its specific design flaws. Always consider testing another cable and checking connectors for bent pins, dust, or debris. Cleaning sockets with a Q tip and isopropyl alcohol helps remove contaminants. Alternatively, try connecting the laptop to the suspected WAN port and verify if it reaches Gigabit speed.
I attempted using a 3-meter Ethernet cable with machined RJ45 ports that didn’t need crimping. When connected, the router showed 1000 Mbps negotiation speed and 150 Mbps on the speed test. I’m puzzled about the issue—should it be the router, the cable, or something else? The D-Link CAT 6 cable was installed by someone else, and a technician confirmed proper crimping was essential for functionality. They also noted that using the direct laptop connection yielded full 150 Mbps. Despite cleaning ports with Q-tip and alcohol and performing a firmware reset, the problem persists. I’m unsure what to try next. After speaking with TP-Link support, they collected all details and promised further guidance, which I’m still awaiting.
They misunderstand the issue, which is frequently discussed on this forum. The main problem often arises when only four wires are used instead of the required eight for 100Mbit, while Gigabit needs all eight. The next frequent case involves full connectivity but with high resistance due to poor crimp quality or a faulty cable, causing it to fall short of standards. This explains why some devices function correctly while others don’t—some need exact compliance, others have flexibility. Unfortunately, many subpar cables, especially certain copper-coated aluminum/CCA ones marketed as CAT6, don’t meet specifications. I even encountered a pre-made CAT6a cable that supported 5Gbit but not 10Gbit.
Good performers can occasionally create issues with connections. This isn't always true. Usually, the problem lies within the cable itself. If you observe that speed adjustments occur when swapping devices, it may indicate a defective cable. Even minor shifts can affect performance, suggesting something is amiss. Takeaway: even fresh cables can have defects. High-quality pre-crimped Ethernet cables of suitable length from trusted manufacturers are generally safe. The fix might be surprising, but sometimes a completely new cable is necessary.