SLOW Internet connection after switch to Cable modem UBEE DVW3201

We change ISP's going from DSL to the cable companies gateway modem with speeds up to 50Mbps download.

Equipment is a UBEE DVW3201b which supports coax and telco services for internet w/TV and phone.

All systems are running near the supported speed of 50Mbps but my Inspiron 5735 running Win8.1.

Another Win 8.1 Dell Inspiron 5535 with wireless 1704 gets almost 40Mbps download and with my wireless 1705 I can barely get about 2.5 to 3Mbps(almost like I got with our old DSL connection with 5M support speeds). Obviously there is something dramatically wrong. My system is our primary system that I maintain and setup and should be the last laptop expected to see this issue. Its almost as if I am still using the Verizon ISP connection for DSL rated at near 5Mbps download. That setup was in another home. We had DSL where I am now but just switched to the Cable co, using their UBEE DVW3201b.

Any ideas on what might be happening here? When I look at the Wireless WIFI info it lists 72M when listing the wireless connection popup display in Network & Sharing Center.

I have tried checking everything to see a reason why this disparety. Even our old Vista laptop gets over 20Mbps download. Smartphones get proper speeds as well when doing speedtest from the iPhones.

Havent contacted cable support yet as I didnt want that frustration just yet. I will soon.

Thoughts on what to check or try?