Do I really need a managed switch for this high availability setup? Details inside.

Hey /r/networking

Sorry if this is a dumb question - I'm not a networking admin, but am being forced to wear that hat for the time being.

 

We have a remote office whose firewall we just changed out from sonicwall to Sophos XG Series + Sophos high availability (not my first choice, but we have these firewalls from a decommissioned office)

 

We put in the single firewall for now without HA, and we were running into crazy problems with their core internet connection (allstream) while running completely fine on their backup non business class connection from a different ISP.

 

Awhile later and a few tickets with vendors later, Allstream told us that it appears that our connection is not set to 100/100 full duplex -- it wasn't - we had it set to Auto/Auto.

 

Now, with that said, in order to do the HA, I need a switch between the WAN connection and the two firewalls. Do I really need a managed switch in order to ensure that this connection is 100/100 full duplex all the way through, or is there a better/less expensive/less management way to do this?

 

Thanks a bunch!