local network speed

I have TP-Link Archer C1200 Dual-band Wifi Router through which I've shared my External HDD over FTP. My HDD is connected to the router via USB. It has a USB sharing option that creates an FTP server directly. Now, The issue I'm facing is that whenever I try to access media file over the FTP on...

I just upgraded my router to a Netgear Nighthawk AC1750 and upgraded my cables to either CAT5e or CAT6 and upgraded my 2 switches, a Netgear Prosafe 8 port GS108 in my office and at my entertainment center 60' away, (cat5e), a 5 port Netgear Prosafe GS 105. I have the switches plugged directly...