Laravel Eloquent where field is X or null

I have a table like this:
table
- field1: tinyint
- field2: varchar (nullable)
- datefield: timestamp (nullable)

Now I want to get all entries where field1 is 1, field2 is null and where datefield is smaller than X or null. I already tried something like this:

$query = Model::where('field1', 1)
->whereNull('field2')
->where('datefield', 'orWhereNull('datefield');

but thats not working. I always get every entry where datefield is null. It doesn’t matter what the other fields are. I also tried to split it in 2 queries: First get every row where datefield is smaller than X or null and then (based on it) get every field where field1 is 1 and field2 is null.

The result was the same. Any idea how to do this?