Anyone know how I can speed up write speeds for ReadyShare? C3700-100NAS

I use my modem-routers ready share feature to create a media server where everyone in my household can dump their SD cards to my 128 GB flash drive any time they get full. We're usually moving between 4-64 GBs each time depending on the person so it could take a while. Windows says my current write speed is 750KB/s. My internet upload is 2mb/s. Is it possible for my internet speed to be faster than my network speed? I have 4 bars of wifi so i should in theory be able to go up to 100mb/s, right? How to speed up my write speed?