RN10400 possible virus on all my file extensions have QWEUIRTKSD file after them and the wont open

The PCs are infected, so you need to begin

1. disabling SMB on the NAS using the web ui
2. disinfect the PCs using antivirus or malware removal software.

Files on the PC could also be encrypted of course (though I have read some posts on this particular ransomware that say only network shares were encrypted).

Then you can factory reset the NAS, and restore the files from a backup that was taken before the ransomware infected your home network.   

If snapshots are enabled, then you can alternatively try rolling back to a snapshot that predates the ransomware attack.  Do this from the Web UI, if you access the NAS using file explorer before you restore it, then you will likely just reinfect the PCs.

Hopefully the restore attempt you've already done hasn't encrypted your backup drive.  If it has, your only option is to pay the ransom and hope that they actually do give you the decryption key.