When I turn on the power, the Ethernet connection drops right away.
When I turn on the power, the Ethernet connection drops right away.
My setup has a Cisco EPC 3925 coax cable modem, a long plastic connector UTP CAT5e cable that is about 30 meters long, and an ethernet card from Marvell Yukon. The problem starts when you turn on a tank-less gas water heater or an electric oven; then the connection drops for one or two seconds before coming back online. It never disconnects over WiFi.
All three devices are in different rooms and far apart from each other. There are mostly 2-prong outlets in my flat. I ran the UTP cable close to the electrical meter and parallel to the power lines, about 10 cm away. Moving it further away didn't help at all. Turning off energy efficient ethernet or green energy features didn't fix it either. Changing my ethernet card from Marvell Yukon 88E8071 to Lenovo P24h-2L Realtek RTL8153 and using a ThinkPad universal USB-C dock 40AY0090EU also did not work. Running on battery power didn't help either.
When I tried checking the connection with "ping -t 8.8.8.8," there were no drops, but only this new setup worked: Cisco EPC 3925 coax cable modem plus 35 m UTP CAT5e cable (plastic connectors) plus TP-Link WR740N v2.5 router and 5 m FTP CAT6 cable with metal connectors plus Marvell Yukon 88E8071 ethernet card.
Can I fix this problem without adding another TP-Link router, and what magic does the TP-Link router use to keep the connection alive?
That number is interesting because it can be reused by others. A 3925 was a very popular router from Cisco. What if you try using a TP-Link router as a switch? You turn off the DHCP server and then plug two Ethernet cables into two LAN ports. This isn't the best way to use it, but it won't hurt your speed or performance when acting as a switch. It's strange stuff though. When I first read this, I thought both the heater and the over were very heavy electrical loads until I realized one of them is actually a gas water heater. Depending on the model, there might not be any wires connected at all, just a small spark if it uses electricity for ignition but no power after that. It almost certainly must be your modem you are talking about. You run the laptop on battery which means you are completely cut off from any power source. You tried other Ethernet cables too, so it is unlikely the NIC (network interface card) itself is broken. Although still possible, it might be your Ethernet cable instead. There are huge amounts of fake Ethernet cables sold mostly because copper metal prices went up. The most common ones you see are flat cables where the wires are much thinner than real standard cables and they have more problems with a proper official one. What you really want is pure copper wire without CCA (copper clad aluminum) and the right wire size, like 24 AWG or bigger. If the seller's ads don't list these details about your cable, it is highly likely that fake ones are inside. Reputable vendors usually highlight these exact specs because they know about fakes and want to prove why their cables cost a little more than just using regular ones. The cable you have with metal connectors is probably a shielded cable but those don't do much in a home setting and could even cause interference if not properly grounded. You need a special ground wire hooked up to the shield, but that doesn't exist in consumer gear; it's mostly used for industrial or data center setups. If your other specs (like wire size) are okay then you just overpaid.
Hey there! Thanks for checking in. Using my TP-Link router as a switch actually keeps my connection steady. About that water heater, it's called a De Dietrich MCR Home 20/24 MI and uses electricity. It costs 84 watts of power. This thing is also used to heat the house, so it works automatically in one way but causes no drop when I switch it off; that makes me wonder why something feels wrong. My oven takes about 2 kilowatts of power on the other hand. A microwave doesn't cause a connection drop even though it uses 1,1 kilowatts. What about my Ethernet cable? It's a stranded Alantec 4x2x26AWG bought from a reputable store and checked by an electrician. The specs say it is pure copper, not that 22-24 gauge wire. It works fine with the TP-Link router and gets the maximum speeds my ISP promises. Installing this 35-meter UTP cable was fresh; the cable itself was bought new too. What about that shielded cable? I don't think the shielding is doing anything useful, but I'm using what I have at hand. If I had a short unshielded one, I might check if it would make any difference. I was surprised when the TP-Link router fixed my problem and I don't understand why either. I also thought about powering a 3925 device through a battery, but buying even the cheapest UPS is an expensive check.
You could try buying a surge protector, because most devices already have built-in protection for power. Since your 3925 has a standard power block, maybe switching to a different one would fix it. A 1.2-kilowatt unit can easily cause a voltage drop, which might make things break down. But only an 84-watt device could really be the culprit because that's too small to create a drop on its own; so there must be some weird signal messing with things. However, I don't think it is about direct power trouble since your modem would still have this problem even if you plug in a TP-Link router right behind it. So, for instance, if it just reboots really fast that means something bad happened regardless of the router. It's much more likely there is interference between the ethernet wires and the power cords than an electrical issue entirely. This is very rare but maybe the Cisco modem is super sensitive and has a weird problem when it talks to your computer instead of the TP-Link. If you plan on spending any money, I'd just use that for replacing the Cisco since it is so old and outdated. The cheapest fix would be to keep using the TP-Link as a switch and ignore this mess for now.