Undefined method error using selenium ruby grid

I am running a basic test to log into a page. When I run this test via a Selenium grid I get:

Failure/error: @driver.navigate.to "https://website.net"
NoMethodError: undefined method 'navigate' for nill:NilClass.


I can confirm the test runs successfully when I run on my local PC without the grid. Do I need to change the method navigate to something else, I can't understand why it won't work when I run it on the grid?

navigate

require "selenium-webdriver"
require "rspec"

#remote capabilities
caps = Selenium::WebDriver::Remote::Capabilities.new
caps['platform'] = 'WIN10'
caps['platformName'] = 'WIN10'
caps['browserName'] = 'chrome'
caps['version'] = '67.0.3396.99'

@driver = Selenium::WebDriver.for(:remote,
:url => 'http://172.16.74.114:4455/wd/hub',
:desired_capabilities => caps)

describe "navigate to website" do
describe "signin to website" do
it "Confirm the user can successfully signin" do

@driver.navigate.to "https://website.net"
puts @driver.manage.window.maximize


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