One of 2 domain servers went down and I can't connect to SQLServer on the other

2 AD Domain Controllers one 2008r2 and the other 2016. FSMO roles are all on the 2008r2
2016 is only on line during a convention where we need quick backup
I disconnected the 2016 server from the network to simulate the 2008r2 going down
connected a workstation in a separate physical network to the 2016 and I get network errors trying to connect to SQLServer (both SQLServers are 2014) from the workstation
I can connect to the server on the 2016 using SSMS from the server itself but not from SSMS on the workstation
sql Browser is running on the server on windows 2016
can ping the windows 2016 server from the workstation
both sqlservers are running instances called <servername>\sqlexpress
when I browse in the connection box on SSMS for network server on the 2016 windows server the network server comes back with just <servername>. I reverified that the running server was the named instance
I have rebooted both machines and logged in as an AD Administrator

I have run out of things to try.

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