Work around is to use the -o option and specify KexAlgorithms with the correcct option.

ssh -o KexAlgorithms=+diffie-hellman-group1-sha1 admin@192.168.11.1

https://unix.stackexchange.com/questions/340844/how-to-enable-diffie-hellman-group1-sha1-key-exchange-on-debian-8-0#340853