[Very slow connection] Troubleshoot Synology NAS over Teamviewer

I have a Synology NAS. I use a laptop to connect to the wifi. The NAS is connected via a ethernet cable. Opening the network drive over wifi takes very very long. Transferring files are impossible. I am able to see the folders on the NAS though. Need help fixing it over teamviewer. Once you have fixed the problem and we are able to transfer the files, this task is complete and we will pay.