Yes and No. The following scenarios would help you undertand how wifi extenders can slow down or increase internet speed. Also check out our recommendation on how to resolve this problem.
How wifi extender slow down internet speed
Assume that you have a wireless router at home. The wireless router is placed in the main room. A wifi extender is setup in the bed room next to the main room. You were sitting in the bed room and have now moved to the main room.
But you are still connected to the wifi extender and not to the wireless router which provides better signal strength in this case.
In this scenario , all internet traffic would first go to the wifi extender and then to wireless router , which would then be forwarded to internet.
This would result in slower internet as compared when you are directly connected to the wireless router.
Does wifi extender increase internet speed
Assume that you did not have a wifi extender in the bed room. In this case, you would need to connect to the main router which is installed and setup at the main room.
In this scenario, the wifi signal strength would definitely be weaker as opposed to a scenario where there is a wifi extender setup in the bed room.
But by having a wifi extender in the room, the overal performance of the internal network is increased , resulting in increased internet speed.
A poor wifi signal strength would decrease the performance of the internal network and would result in slower internet speed whereas a stronger wifi signal strength would result in increased internet speed.
It should be noted that the internet speed is set by the ISP. So, the actual internet speed is not affected by both scenarios. The internet speed which is experienced on the internal network varies based on the scenario.
Recommendation
If you are using wifi extender in your setup , ensure that you are connected to the wireless router , when you are in closer proximity to it as compared with the wifi extender.
If your home is large, you could probably use mesh routers instead of wifi extenders. When mesh routers are used the switch over to the mesh unit with the best wifi signal is performed automatically.