Wired connection to router and wi-fi very slow to hard-wired to wall connection

[kmviars]

We just upgraded our internet to 100Mbps, but were still getting about 3.5 Mbps through our speed tests. We called our internet company, and they said it looked like we were getting 100 on their end. They had us plug directly to the wall, rather than the router and the speed test shows 100 Mbps.
The router is maybe two years old. We also have an extender for the network upstairs. What settings/trouble shooting should we do to fix this??

 

[anotherdrew]

So, WiFi or wired to the the router and you get 3.5 Mbps ... bypass the router and you get 100 Mbps. Sounds like something is up with the router.

Possibilities ...
Bad cable ... unlikely in this case, but so easy to check.
Bandwidth limiting as part of a QoS (Quality of Service) setup.
Port filtering or firewall rules slowing things down.
Something else in the configuration ... go through the setup.
If all else fails, do a factory reset on the router (do write down any important configuration information because everything gets reset .. WiFi setup, passwords, etc).

Let us know what you find out.