Local + Internet synchronized Storage Servers?

Can NextCloud be used to replace an aging Windows server for file sharing such that local users can access file storage via smb / cifs?

Further, can a local server + Internet based server (such as with Linode) be set to synchronize with each other?

We have a site that has a poor ISP with multiple outages a month. I’d like to set up a server onsite and a mirror on a hosted server like Linode that will allow local workers to still access the file shares as they would have via our Windows Server while having the benefits of a backup of everything on the Internet with the capability to share things in a Dropbox / CloudApp like fashion with anyone that may need to access files remotely and that may be shared.