After three years of use, China Telecom’s optical modem network has become increasingly laggy. Is the broadband slowing down? After taking a look at the data, 80% of the time the cat is tired.

My TEWA-750G was delivered by China Telecom when broadband was installed in 2022. After using it until the end of last year, my wife began to complain about the lack of network connectivity every day. Symptoms are complex: The video occasionally spins in circles, the TV screencast cuts out every now and then, and WeChat voice calls occasionally blur for half a second. At first, I suspected that the broadband speed was being slowed down, so I called 10,000. The account speed reported by customer service was still 300M, and it didn’t change at all. Follow again The article about Gigabit port and 100 Mbit port I checked the network cable socket, and yes, the network port 1 Gigabit port is plugged in.

Then I remembered that there was a control group at home: The ZTE F7015T owned by my mother-in-law has been installed for about the same time and has been used for the same age, so the whole family has nothing to do with watching TV shows. The same operator, the same speed range, one card is stuck and the other is not stuck, then the problem is probably not in the broadband itself. That weekend I went through the accounts of both Cats, and the conclusion was quite counter-intuitive.: The broadband has not slowed down, it’s because my cat is tired. This article writes down the judgment process and numbers, so those who have old cats at home can check it out.

First distinguish: The old light path and the tired cat are two diseases

Many people think of light decay when they hear "optical modem aging". This direction is not wrong, but it is only half right. How many years can a optical modem be used? Here I have calculated the loss of light in detail.: The aging of the optical path is like "eyes blurred by light". The symptom is that the light decay reading is getting higher year by year, and the network speed is also decreasing. This progress 192.168.2.1 You can diagnose eye failure by looking at the backstage, and if it exceeds -28, you need to report for repair.

But there is another kind of aging that has nothing to do with the optical path, which is "the brain can no longer move" - ​​the optical modem is essentially a low-profile small computer that dials up, forwards, has WiFi, and runs ITMS remote management, all on the same CPU and one or two hundred megabytes of memory. This CPU will not suddenly break down, but it will become more and more difficult. The characteristics of this disease are: The light decay is normal, the light is all green, and the account speed is not moving. But at night when all the devices at home are awake, it starts queuing up. The one I have at home is the standard second type. The light decay is -24 or so all year round. It is very stable, but it suffers from lag.

The medicines for the two diseases are completely different: When Guanglu is old, call 10,000 to change the cat, it’s free. ； When the cat is tired, do subtraction first. If the cat cannot reduce, consider changing it. Don't just report it for repair when you come up. The technician will come and check that the light decay is normal and the speed is up to standard. It's a waste of time and you have to sign a work order.

The evidence that my cat is "tired" is laid out in three numbers.

Whether the cat is tired or not, it doesn’t matter what I say. I caught three numbers and checked them with two cats. Right at the door 192.168.2.1 In the background, the useradmin account can view most of it. The super management entrance is not needed. It can be viewed without configuration. An ordinary account is enough.

The first one is memory. On the system status page, both cats show a total memory of 128M. The one at my house has only about 10 MB free all year round, and the one at my mother-in-law’s house still has more than 40 MB free. It is also a home with seven or eight devices installed, and the difference of more than 30 MB is due to the monitoring plug-ins, operation logs, WiFi statistics and other things installed in the past three years. The performance of memory bottoming out is particularly typical.: It's fine when no one is using it during the day. But when all the devices come online at night, it starts to use up memory and the latency becomes erratic.

The second one is CPU usage. There is a CPU usage rate on the background status page. During the day, I see it is more than 10%. At 8 or 9 in the evening, when the TV, tablet, two mobile phones, and sweeper are all online, I refresh the CPU usage rate. The one I have at home can reach 70 or 80%, and it can reach 90% or higher from time to time. The one at my mother-in-law’s house was about forty at the same time. It makes no sense to look at this number alone for one day. I only dared to draw a conclusion after reading it for three nights.

The third most intuitive: With the amount of machine. My home used to have nine devices installed without any problem. Last year, the sixth device started to go offline. The sweeper went offline in the middle of the night and the camera occasionally rotated in circles. Restarting the optical modem can relieve the problem overnight. The number of machines has shrunk from nine to six. This is either a metaphysics or a chain reaction after the CPU and memory margins bottom out. Is Cat WiFi Enough? I mentioned earlier that the number of machines this batch of gateways can carry is only ten, which is the level of new machines. After two or three years of age, the actual number of machines that can be carried will be further discounted.

Don’t be in a hurry to change cats. Do three things to reduce your burden first.

After confirming that the cat was tired, my first reaction was not to replace it - Telecom had to go through the process to change the cat, and when the new cat was brought back and the ITMS was pushed to configure, the plug-ins that should be installed were still installed. First offload it, and many families will be able to recover after doing these three things.

The first thing is to turn off the WiFi that comes with optical modem. This is the biggest item. Optical modem's WiFi and its dial-up forwarding use the same CPU. If you have your own router at home, the two optical modem signals starting with ChinaNet will be a pure burden. My mother's house was taking care of it at that time. The article about Guangguangmao WiFi After shutting it down, I moved all the equipment to my own router, and the old router didn't go offline again the next day. When turning it off, remember to turn off both dual-bands, don't just turn off one.

The second thing is to clear the equipment list. In the list of connected devices in the background, you can find several things that are no longer at home.: There are second-hand old mobile phones, tablets that the neighbor used three years ago, and TV boxes that have been thrown away long ago. Some of these afterimages also occupy DHCP entries and session numbers. I cleared out seven old equipment and clicked on the equipment I was using The fixed IP article After binding a fixed address, the routing table is much clearer.

The third thing is that restarting depends on the timing. Scheduled restarts are not a panacea, but old cats do need them. I set up a one-minute power outage at 4 a.m. every Wednesday. I chose this time because the whole family has the least equipment and ITMS basically does not push configurations in the early morning. Restarting can clear the memory and reset the session table, which is a real life extension for tired cats. If your home already has a rhythm of "stopping and restarting every night", do the first two things first. Restarting alone will cure the symptoms.

After the load reduction is completed, the card is returned. Two steps to confirm whether you want to change it or not.

After completing the three load-reducing tasks, observe them for one to two weeks. If the lags at home are visibly reduced, call it a day, this cat can still fight. If the evening peak is still shaking and the CPU is still at 90%, then it’s time to consider moving it. Don't pay for it yourself at this time. Telecom's optical modem is the operator's asset. If it is broken or old, it will affect its use. It does not cost money to repair or replace it with a new one. This is The free replacement article There are clearly written rules.

Before reporting for repair, I suggest you keep your own evidence.: Save a screenshot of the CPU usage, light attenuation readings, and speed test results during the evening peak. When calling 10,000, read the numbers directly and say, "The equipment operating load has been high for a long time. Request to replace the terminal." It is much better than saying, "The network is stuck." When the master comes to your home, he will most likely measure the light attenuation and speed first. If both are normal, show him your memory and CPU usage. This will be the basis for replacement.

There is also an accelerator: Increase broadband. If you originally planned to upgrade from 300M to Gigabit, that's just right. Upgrading requires a new modem. The operator will take the initiative to replace you with a new Tianyi gateway that supports 10G optical ports. After I replaced this one, I can easily connect it to nine devices at home. Upgrade the broadband first and then talk about the modem. It is more cost-effective to do two things in one process than to replace the "card" separately.

After one night of investigation, I compiled this list

The old cat at home is getting stuck. Follow this order and don’t skip steps.:

After this set is completed, whether the problem lies in the broadband, optical path, optical modem performance or the wiring in your own home, you have all been screened. At the end of my life, I upgraded to Gigabit and replaced it with a new one. The old TEWA-750G was wiped clean and put away in a drawer, and kept as a backup machine - if someone's cat explodes one day, it will be enough to save an emergency.