@MisterChew 

I am going to point you to a thread that we had last week that may hopefully answer some of your questions:

How does 1.3Gbps WiFi only get 212Mbps????

The key things to remember is that the connection speed that is being tested is actually the speed to a specific server location. This means that there are a huge variety of factors at play when testing and comparing speeds, especially across brands and across speed test methods/services. Can you try to use another speed test service on both setups and try to use a wired connection to determine what is slowing the system down. 

When placing an ISP modem into bridge mode, there are settings that can also be changed that may affect the speed of the overall connection and security. I would attempt to log in to the ISP modem through its Web Interface and ensure that the settings are how you would like them to be configured for your new network.