what do you mean with minimum bandwidth required? I think there is no limitation to the patch Manager itself, it's more a question how long can you wait, until a normal patch is downloaded to a client. If you go into the network settings of your agents distribution and patch settings, you can define, how much percent of bandwidth the Agent is allowed to use on a WAN or a LAN link. Is this helpful?
What Christian said.
If you have a site that's connected via a 56 Kbps modem, then we will cope with that ... it would take qutie a while to download the latest Windows 10 update via that link, but we'd get there. Eventually.
Alternative methods may be better in some situations (I've had customers send software packages / patches around via USB-keys / CD's over the years to "tiny link" sites that had tiny modem lines) and using a local device as either the preferred package server or "just" for peer download, for example.
We've got capability & trickery for both. More context & information from your side would be helpful to provide better advice though.