I see partners that experience this often, especially over time. It is completely natural to a certain extent that sex will wax and wane over the course of your relationship. However, what I am most intrigued by is that you say sex is better away from home. Has something happened at home that has turned you and your partner off, or altered the atmosphere of the home? I would spend some time with your partner and look at what was so exciting and great about sex on vacation. Is it the suspension of reality and responsibilities that make it easier for the two of you to connect? Does the freedom of being away also relieve you or your partner of certain inhibitions? Does the bedroom represent some sort of difficult situation or time in your relationship that now makes it harder for the two of you to get in the mood when home? Has sex been solely kept to the bedroom for the course of your relationship where it has become mundane?
Go over these questions very honestly with each other, and do some soul searching. What kind of sex do the two of you want to have? Can some easier changes be made, or does this require more intensive action? If the problem is escapism, then perhaps planning the time where you two can turn off your phones, or at least put them down for a few hours, and disconnect from other parts of your life to focus solely on each other could help. Find a way to suspend reality similarly to how you feel while away on vacation. Plan a stay-cation: block out some time (even a day) where it’s like you’re on vacation, but really just at home. Maybe a little planning for sex is the key to help get you both in the frame of mind, and clear out all the other stuff.
Also, try getting freaky in other parts of the house to see if your relationship just requires a little spice. I highly recommend the island in the kitchen if you have one. If the problem is atmospheric, have you considered redecorating? Something like new sheets and lighting can make the bedroom more like a hotel than home. Also, I’d say make the bedroom more like a haven. It is going to be hard to feel sexual if there is a TV and computer going on in the same room as your love nest (unless said TV/computer is streaming porn or sexy music). There is clearly something the two of you need to overcome. If sex is mundane, then try referring to a few of my other Q&A pieces and articles on this website by the multitude of writers coming up with ways to have variety in your sex life. If all else fails, I may recommend you contacting a professional to help you two find your way back to your intimacy.