Stop dog barking at fox during the night.

Hoping to get some advice. My dog, 18 months spaniel cross, view all foxes as her arch enemies… It used to be that if she was in the garden and she heard / saw a fox she’d go nuts, I’d send her back inside and she would calm down. Now however she reacts to them even if she’s indoors. To the point she’ll be sleeping at the bottom of my bed and suddenly race across the house to our back door and bark like she’s the most vicious beast at a fox playing in our back garden at like 4am… if I use a stern command or move her away from the door she stops but I’d rather not be woken like that in the first place and neither does my neighbours I assume🫣 I’m starting to think the fox comes to wind her up! Anyone experienced a similar thing or have suggestions on how to deal with this would be much appreciated as it’s happened every night this week 😩