To test the RADIUS server directly, execute inside the VM:
sudo radtest user1 testpwd localhost 18128 testing123
mysql -u root -p secret psecret radius
SELECT id, username, attribute, value, op FROM radcheck WHERE username = 'user1' ORDER BY id;
SELECT id, username, attribute, value, op FROM radreply WHERE username = 'user1' ORDER BY id;
SELECT groupname FROM radusergroup WHERE username = 'user1' ORDER BY priority;
INSERT INTO radpostauth (username, pass, reply, authdate) VALUES ( 'user1','testpwd','Access-Accept', '2018-01-26 22:07:14')