I cannot connect to the scanner function of the FS-1118MFP.

This can have several reasons; first the cable can be the problem, second the installation or the setup of the twain driver. And there can be a conflict between different installed twain drivers on your pc. And last but not least, a combination of the above three. Try another USB cable, delete and reinstall and reconfigure the FS-1118MFP twain driver.

If there are more twain drivers, delete them all (also the Kyocera drivers), reboot the pc and reinstall and configure the FS-1118MFP twain driver. Test again, and if everything is ok you can consider reinstalling other twain drivers one by one until the problem reappears. Then you know which driver is conflicting and you need to remove.