This could be something one-off, for example if a device starts updating and downloading a lot of data, but also something more common, for example a device that creates an automatic backup every time it connects or starts to sync files with another device on the network.
have some malware
Of course, another reason may be that this device has a malware. If, for example, we connect a computer and see that the Internet connection starts to go wrong, maybe that PC has a virus and that causes it to consume a lot of resources without us realizing it. We could have major problems, as that could mean a hacker is using the connection and putting our privacy at risk.
This always needs to be checked. If it is a computer, you can see which processes are consuming the connection at all times. As soon as you spot something suspicious, you can scan for any issues that might be there. A good idea is use an antivirus and perform an analysis to detect threats. For example Windows Defender, Avast or Bitdefender are some interesting options.
However, although this problem is more common on computers, it can also affect mobile devices. You must always maintain security, keep everything updated and thus prevent malware from compromising the security of the devices that we have connected and also the proper functioning of the connection.
Another issue to keep in mind is that there may be a hardware problem. If when connecting a device you see that the Wi-Fi starts to go wrong in the rest, perhaps that device has a problem. Mind you, normally this happens when you connect it via network wire. It could cause failure to connect it this way to the router and cause it to shut down or start to go wrong.
If for example a ethernet port of the router has some failure and you connect a computer to it, maybe that causes the connection to be cut. This will not only affect that device that we connect, but also any other device that has connected to that network. It could also cause errors for those connecting to the router wirelessly.
Also, this can occur from overheating. If the router overheats, what it does to protect its components is to shut down and stop working properly. If there is any fault at the hardware level, that could cause overheating and lead to problems for other devices.
Subtract power from the repeater
Maybe the problem comes when you connect a device to a certain access point. If for example you use a Wi-Fi repeater or a PLC to connect to the network, it is possible that when you connect something to one of these devices it starts to go wrong. This is so since sometimes they are very limited and do not work well when we connect more than one device. It is not normal, but there are economic models that start to go wrong quickly.
This is accentuated when we make intense use of that device. For example, a computer that we connect to a repeater and start to download files, watch streaming videos or anything that can consume more than necessary and put the operation of that repeater that we are using in trouble.
To prevent this from happening, it is best to use a Wi-Fi amplifier, PLC or Mesh system that is guaranteed, has good bandwidth and is not easily limited as soon as we connect a device.
One more issue to keep in mind is that the device that we connect could generate interference. This can cause Wi-Fi to stop working properly on other computers. When can this happen? Think, for example, of a television that you connect via Wi-Fi. Maybe you have a computer right next to you that also connects wirelessly. When you turn on that PC, being next to the television could cause interference and cause the network to not work well.
Keep in mind that you can use both the 5 GHz band and the 2.4 GHz band. It is the latter that usually has more interference problems, especially when there are many devices connected or you have something nearby that can generate problems, such as a microwave or a device that uses Bluetooth, since both cases work in a close frequency.
If you are facing this problem, our advice is to try to connect to the 5 GHz band whenever possible. In addition, it is a good idea to separate the devices and never have them close to avoid possible interference that may occur.
In short, as you have seen, it is possible that connecting a certain device to the network could affect the rest of the connected devices. This can happen for different reasons, such as interference, hardware failure, excessive bandwidth usage, or even malware.
To avoid problems of this type, it is good to keep the devices in good condition, always updated and protected. This will help to protect the software, but also to ensure that the hardware is in good condition to be able to access the network without interruptions.