Strange speed issues... The only solution is to restart the router.
Strange speed issues... The only solution is to restart the router.
Every few weeks the connection becomes quite sluggish, dropping from 40Mbps to 2-3Mbps for both download and upload. Ping times remain steady, but latency spikes occasionally. We changed the DSL cable and even the router, yet the problem persists. After a restart, it sometimes works for days or weeks before returning. It’s proving difficult to pinpoint the exact cause.
It seems the DSL cable is placed very close to the power supply—this has been consistent for years, only recently did an older computer (acting as a NAS) start showing issues. It was running a Pi-hole on that machine, but its Ethernet supports 1Gbps and hasn’t been throttled. The ISP has visited twice, suggesting no hardware fault, just changes to cable or settings.
Network setup: the router uses only one Ethernet port. The cable runs throughout the house to a switch with 2Gbps capability, connecting three computers. Wi-Fi handles about five to six devices. When speeds drop, the admin interface claims it recognizes the correct DSL rates.
@Depstros 1. I’ve noticed phone lines and even Ethernet running alongside electrical wires without any problems. Still, poorly shielded cables can potentially face electromagnetic interference. “DSL cables” are basically standard landline phone cables, according to what I recall, and they have very thin insulation. Check as much of the cable layout as you can to spot any exposed or twisted sections, and if possible, keep them away from electrical systems.
2. DSL works well in rural spots with few phone options, but speeds drop the farther you are from the ISP. You can’t really change much about this. What rates does your ISP actually charge? Remember, with asymmetric connections—especially DSL—overloading the upload (which is usually slower than download) will hurt download speeds.
3. To figure out if the lag comes from your ISP or your setup, you need to test speeds in different environments: directly connected to the DSL modem/gateway, through your router (if separate), and then via WiFi.
4. Knowing the exact brands and models of your networking gear can help identify if the issue is hardware-related.
I mentioned earlier that the cable has been modified and the problem is still ongoing.
For many years, speeds have remained consistent—typically around 40Mbps down and 8Mbps up (paying 50Mbps down and 5 Mbps up).
When testing via Ethernet, results are nearly identical to those on Wi-Fi.
My setup includes a ZYXEL VMG3625-T50B router and a NETGEAR ProSafe Ples GS105Ev2 switch.
Are you seeing the DSL line stats on your router? I’d track them to determine if the slowdown is due to the actual DSL connection or the router itself. Testing the main cabling shows only occasional errors when appliances are used, and the issue resets after rebooting. Did you verify the timing of the slowdown—did unplugging and replugging the DSL cable resolve it instead of a restart?