Cannot SSH into Cisco switch or pfSense router from Mac Mini (macOS High Sierra 10.13.6)

Errors message in Terminal are (switch 1st, router 2nd):

MacMini:/ MacAdmin$ ssh NetAdmin@192.168.3.2 #Switch
Unable to negotiate with 192.168.3.2 port 22: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1

MacMini:/ MacAdmin$ ssh NetAdmin@192.168.3.1 #Router
Unable to negotiate with 192.168.3.1 port 22: no matching key exchange method
found. Their offer: curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256

UPDATE 1:
Using Pete's suggestion below, I receive this error about "no matching MAC found"

MacMini:/ MacAdmin$ ssh -oKexAlgorithms=+diffie-hellman-group-exchange-sha256 192.168.3.1
Unable to negotiate with 192.168.3.1 port 22: no matching MAC found. Their offer: > hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-ripemd160->etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,hmac->ripemd160,umac-128@openssh.com

Here is the output of my SSH config file (/etc/ssh/ssh_config):

MacMini:/ MacAdmin$ cat /etc/ssh/ssh_config
#   $OpenBSD: ssh_config,v 1.33 2017/05/07 23:12:57 djm Exp $

# This is the ssh client system-wide configuration file.  See
# ssh_config(5) for more information.  This file provides defaults for
# users, and the values can be changed in per-user configuration files
# or on the command line.

# Configuration data is parsed as follows:
#  1. command line options
#  2. user-specific file
#  3. system-wide file
# Any configuration value is only changed the first time it is set.
# Thus, host-specific definitions should be at the beginning of the
# configuration file, and defaults at the end.

# Site-wide defaults for some commonly used options.  For a comprehensive
# list of available options, their meanings and defaults, please see the
# ssh_config(5) man page.

# Host *
#   ForwardAgent no
#   ForwardX11 no
#   PasswordAuthentication yes
#   HostbasedAuthentication no
#   GSSAPIAuthentication no
#   GSSAPIDelegateCredentials no
#   BatchMode no
#   CheckHostIP yes
#   AddressFamily any
#   ConnectTimeout 0
#   StrictHostKeyChecking ask
#   IdentityFile ~/.ssh/id_rsa
#   IdentityFile ~/.ssh/id_dsa
#   IdentityFile ~/.ssh/id_ecdsa
#   IdentityFile ~/.ssh/id_ed25519
#   Port 22
#   Protocol 2
   Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc
   MACs hmac-md5,hmac-sha1,umac-64@openssh.com
#   EscapeChar ~
#   Tunnel no
#   TunnelDevice any:any
#   PermitLocalCommand no
#   VisualHostKey no
#   ProxyCommand ssh -q -W %h:%p gateway.example.com
#   RekeyLimit 1G 1h

Host 192.168.3.1
HostkeyAlgorithms ssh-dss,ssh-rsa
KexAlgorithms +diffie-hellman-group1-sha1
MacMini:/ MacAdmin$ 

Update 2:
I don't know how to properly edit my SSH config file (/etc/ssh/ssh_config) but I have a decent workaround with this command:
ssh -oKexAlgorithms=+diffie-hellman-group-exchange-sha256 -oMACs=hmac-sha2-512-etm@openssh.com RouterAdmin@192.168.3.1