DIAGNOSIS After a factory reset, your computer is likely still trying to use old network information. It's not getting the correct IP address from the freshly reset router.
FIX You need to force your computer to get a new address. 1) Unplug the Ethernet cable from your computer (if using one) and connect via Wi-Fi. The router's default Wi-Fi name (SSID) and password are on the label on the bottom of the unit. 2) On your computer, open a command prompt (Windows) or terminal (Mac) and type `ipconfig /release` then `ipconfig /renew` (Windows) or `sudo ipconfig set en0 DHCP` (Mac). 3) Try accessing http://192.168.50.1 again in your browser.
IF THAT DIDN'T WORK Try a different browser, or clear your current browser's cache. Also, make sure you're not using a VPN or proxy, as those will block local network access. As a last resort, connect your computer directly to the router's LAN port with an Ethernet cable and try the address again.
HEADS UP The default login credentials after a reset are username "admin" and password "admin." You'll be forced to change the password on first login. If you set a custom IP address range before the reset, the router will have forgotten it, so 192.168.50.1 is the correct address to use.