Go mongo-driver cannot connect to mongodb container

I am using a simple go CRUD api that uses MongoDB and moving it to docker containers. I cannot connect to the MongoDB for some reason. After researching I cannot find a solution.

I have tried:

• Exposing/publishing ports, so I can use the container name instead of 'mongodb:localhost:27017/' when trying to connect to the client.
• I have also removed any network config in my compose.yml file so that there is no network confusion.

This is my compose.yml file:

version: '3.4'
    
services:
    mongodb:
      image: mongo:4.0.4
      restart: always
      ports:
        - 27017:27017
      
    mongo_todo:
      build: ./mongo_todo
      ports: 
        - 3000:3000
      depends_on:
        - mongodb
      
    go_todo:
    build: ./go_todo
    ports:
      - 80:80
    depends_on:
      - mongo_todo

This is my mongo_todo Dockerfile:

FROM golang:1.14
WORKDIR /go/src/app
COPY . .

RUN go get -d -v ./...
RUN go install -v ./...

EXPOSE 80

And this is how I am trying to connect to the client:

// Set client options
clientOptions := options.Client().ApplyURI("mongodb://mongodb:27017")

// Connect to MongoDB
Client, _ = mongo.Connect(context.TODO(), clientOptions)

// Check the connection
err := Client.Ping(context.TODO(), nil)
if err != nil {
    log.Fatal(err)
}

The program is logging a Fatal error when trying to ping the client to check the connection.

Log output:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x2e0 pc=0x9a798c]
goroutine 1 [running]:
go.mongodb.org/mongo-driver/mongo.(*Client).Ping(0x0, 0xd61e20, 0xc000028030, 0x0, 0x1, 0x0)
/go/src/go.mongodb.org/mongo-driver/mongo/client.go:229 +0x21c
main.main()
/go/src/app/main.go:30 +0x16f

I understand that it is some kind of networking issue but I have no idea why it is not working and I have a feeling that there's something simple that I am missing.

Please ask me for more information if needed and thanks in advance for any help.

Edit: I can ping the hostname mongodb from my go_todo container so not sure if it is a network issue.