The wireless network speed (throughput) will usually be affected by these factors as shown below, so you should try to do some adjustments to mitigate these issues.
Interference – Interference of cordless phone, microwave or other electronic devices that utilize same 2.4 GHz or 5 GHz radio frequency, so don't place the wireless router or access point nears to these electronic devices or turn off these electronic devices to minimize this kind of interference. You should consider to configure 5 GHz radio frequency on your wireless router or access point if it's supported, because less interference is expected with less electronic devices utilize same 5 GHz radio frequency.
In addition, the interference between wireless networks that use the same channel will reduce the network throughput as well. You can use this free wireless scanning tool to find out any interference that affects your wireless network if you are not sure. How to resolve this interference problem? You can configure wireless router or access point to use different channel and test again.
Signal Blocking – Signal blocking by thick wall or other physical barriers especially at home! If you face this problem, reposition the wireless router or access point in order to get better wireless network performance.
Shared bandwidth – The bandwidth of wireless network is shared among different wireless users, so the more users you have on the same wireless network the slower network speed. In this case, you might think about using QoS (Quality of Service) feature on wireless router or access point to shape the network traffic and improve performance for certain applications or network users.
Distance – If you sit near to wireless router or access point, you will get high and good network speed. However if another person joins the network sitting far from the wireless router or access point, the network speed of both computers will be dropped drastically. The rule is the further your location from the wireless router or access point, the slower your connection will be, and the distance will affect the network speed of other users also.
Mixed Network (802.11a/n/ac, 802.11b/g/n/ax, 802.11b/g/n, 802.11b/g, etc.) – Let's check out this example: In an 802.11b/g/n mixed network, you can get good network speed by using 802.11n wireless adapter if connecting alone, however once an 802.11g or 802.11b user joined the network, your network connection speed may be slowed by half or more. Therefore, you are advised to use the wireless adapters that support same wireless standard (802.11n, 802.11g or 802.11b) on wireless network to have better wireless network performance, and at the same time you can configure wireless router to support particular wireless standard only.
Note: Other than several factors that I mentioned above which you should avoid them from affecting your wireless network performance, you can also play with advanced wireless network settings (beacon interval, RTS threshold, fragmentation threshold, etc) on wireless router or access point in order to optimize wireless network performance. If you are interested, check out this article to know more.
Need a break? Take a look at this video on how to increase your wireless signal and also notice how serious is that guy on the video! This is a real big JOKE!! Hahaha!