Wifi Coverage for Smart WiFi Router

[Skokes]

I currently have a Netgear R6400 Smart WiFi router. I changed internet service providers that changed from a landline to a cable connection. This required my router to be relocated and I lost coverage to my detached garage. Due to the age of my R6400 (2017) would I be better served to purchase a new router or just an extender?  Thanks in advance.

[FURRYe38]

How far is the garage from where the router is? 

A EX series model extender could work. 

[Skokes]

Just over 100 feet (separate building).  Thanks

[plemans]

100ft is quite a distance plus the 2 exterior walls in the building. 

Might not make it that far. 

Any chance you could run an underground ethernet wire? 

that'd be your best option and then just put a router/extender in there (in access point mode)