You can get only 100mbps from your internet connection if your WAN port is 100mbps but your wifi devices will connect at 150mbps with the router so your internal network can be faster than your than your internet connection. In reality though, these 150mbps routers will give you 50-80mbps over wifi even when the connection is made at 150mbps. Don't know why they are rated higher than their actual speed.
Wifi with psk+aes gives 150mbps, the router that you purchased might be more than 150mbps or equal. WAN port might give better speeds, LAN port is 100mbps, i think wan is higher, can you try putting your wire on LAN port(of router) and then try speedtest.
Always spend more and get a router which has
1) Gigabit ports
2) Dual band Wireless ac with 866 Mbps speed (433 x 2)
I have gone for total overkill setup
1) Asus RT-AC88U router (1300 Mbps wifi speed on AC 5 Ghz)
2) Netgear 10 Gb ethernet 8 port switch
3) PC has Aquantia 10 Gb ethernet PCI card
4) NAS also has same 10 Gb ethernet card to serve my home media without any bottlenecks to my Apple TV.
5) Whole house has been wired with CAT7 (Yes CAT7) cables.
I avoid Wifi whenever possible. I can remotely WOL my PC or NAS from my mobile. Gives a sense of total control over my network