In the world of web hosting having a faster internet connection is necessary. You shouldn’t be miser here because you could bottleneck everything here. For most of us, 100 Mbps internet connection is fine, even it is enough to host small blogs, websites, or any other low network intensive web project. I too run a self-hosted cloud backup service for myself from home and it is enough for me while for blogs and website I use bigger and faster servers.
But Gigabit internet is a commodity today, at least for web hosting companies. If your hosting company does not offer a Gigabit internet then a 100 Mbps connection is fast enough to handle the majority of workloads, but it is slow as per today’s standards.
Think, if the network is used by 10 users and each user starts to utilize 10 Mbps, then your server’s network will begin to struggle and any new users have to wait.
Unless the hosted files on server is going to get a massive hit, or going viral; 100 Mbps is enough to handle any small-medium network load. But do note that, for server racks even a Gigabit connection is considered slow, but it is minimum standard. That is why, if the servers are going to be used by multiple users then 100 Mbps internet is too slow.
So for your small server setup, 100 Mbps could be okayish, but not reliable for many users at a time. Get at least a Gigabit connection for the servers and for 100% uptime make sure you buy internet from multiple ISPs (Internet Service Providers) and set fail-overs.