There are several things you can do to test this:
If you are having general network issues, you will not find further answers in this article, which discusses issues with individual devices when the network is otherwise working.
Here are some links that may help:
Let's start with the most obvious:
A reboot of your device or computer may be a good idea if certain functions have stopped working. Sometimes turning the client's Wi-Fi on and off can be enough.
If someone is logged on to a Wi-Fi network that your device can't "see", and you've already checked that the search for Wi-Fi is working, there are two main explanations for this; the SSID is hidden, or there are "too many" networks for your device to display.
Most routers and other access points have a setting called "Hide SSID" or similar. If this is enabled, you have to know the exact name of the network and manually enter it on each device yourself.
If you think a network may be hidden, you can test this with a Wi-Fi scanner — where the network will appear regardless of this SSID setting. As a Wi-Fi scanner will show a wireless network even when the SSID is hidden, this setting does not provide any particular level of increased security, and we do not recommend using it. You can get more advice on SSID setup here.
For more tips on using Wi-Fi scanners, see Locate good channels and bad neighbors with a Wi-Fi scanner.
This is very rarely the case for smartphones or PCs, but some types of devices, such as wireless printers, may have a limit on the number of networks they can retrieve and display.
For example, some will show only the first 10 networks being detected, even if more than 20 networks are available. In this case, it may be necessary to enter the network name (SSID) directly onto the device to connect.
Check that any devices that are struggling to connect or get thrown off the network have the latest system updates installed.
To update your iPhone and turn on Automatic Updates: https://support.apple.com/en-us/HT204204
If you are using a mobile or other device made for a market outside of Europe, or a low-cost product, it may not be able to communicate on the Wi-Fi channels used:
Many low-cost products may also have channel constraints, regardless of which market they were made for. If you have any doubts about what your device supports, check the documentation for it.
To find out which channel your wireless network uses and optionally change it, you need to log in to the settings of your router or access point:
More on finding the best channel on the 2.4 GHz band can be found in: How to locate good Wi-Fi channels and bad neighbors.
The Apple iPhone has a feature called Wi-Fi Assist or Wi-Fi helper, which is turned on by default. We recommend turning this off if you want to avoid your Wi-Fi and mobile network competing with each other once you are connected to Wi-Fi. Especially if you have a mesh network, such as AirTies Wi-Fi, it is better to let the mesh network control where your devices are connected.
You can read more about Wi-Fi Assist and how to enable and disable it here: https://support.apple.com/en-us/HT205296
Wi-Fi is not one standard, but many. Not only are there different versions and "vintages" of Wi-Fi, but there are also a lot of specialized standards that apply, for example, the movement between access points (also called roaming, 802.11r), Wi-Fi Radio Resource management (802.11k), and so on. Each of these standards contains mandatory and optional parts.
Suppliers choose different subsets and implementations. The most well-known initiative to get vendors to be more aligned is the Wi-Fi Alliance, which certifies products with Wi-Fi support. This alliance has hundreds of vendors as members. Apple is the most well-known company that is not a member of the Wi-Fi Alliance and consistently does not certify its products.
If you have a mesh network with client and band steering, such as AirTies Wi-Fi, your network is trying to stay in control of what is the best connection for anyone connecting to the network. At the same time, many of the devices that connect have their own functionality that tries to dictate what kind of connection to accept, in order to ensure the the best experience for the user--as in the Apple Wi-Fi Assist example above. This is especially true for smartphones.
When the mesh network tries to move the phone to another node and the smartphone will not move, you can get a battle where both parties try to prevent the other from making stupid decisions. The client steering in the mesh network wants to make sure that the client is connected to the best frequency band and the most appropriate node in the network, whereas clients, for example, often simply prefer the strongest signal, which in many cases can come from the 2.4 GHz network. If the mesh network withdraws from this battle, the client is in control.
Article by Geir Arne Rimala and Jorunn D. Newth