How many users could be access internet via XG125?

Its not that easy.

User numbers are nowadays only a small factor. A User can consume a entire appliance, depending on what he is doing. If your users only browser in the internet and checking emails or they are working within cloud database services, there is a big difference. 

It is likely you need to verify, if the desired appliance meets your network requirements. 

https://www.sophos.com/en-us/medialibrary/PDFs/factsheets/sophos-xg-series-appliances-brna.pdf

Page 12. 

Does the performance numbers are, what you are looking for? 

Its not that easy.

User numbers are nowadays only a small factor. A User can consume a entire appliance, depending on what he is doing. If your users only browser in the internet and checking emails or they are working within cloud database services, there is a big difference. 

It is likely you need to verify, if the desired appliance meets your network requirements. 

https://www.sophos.com/en-us/medialibrary/PDFs/factsheets/sophos-xg-series-appliances-brna.pdf

Page 12. 

Does the performance numbers are, what you are looking for? 

Thanks.

The XG125 for brower and mails checking. 

Brgds

LIu Wei