Just installed 300mpbs with Panoramic WiFi is Slo

Just had my Cox 300mbps installed yesterday and unless you are really close to the modem it appears that you will not get good wifi coverage in my anyway.  I can seem to get over 15mbps downstairs from the modem. I didn't want to go with the pods as folks have told me that is excessive and the panoramic is capable of handling my situation.  Ideas?