Hello Persus,
Welcome to the community!
What makes you believe that the iPhone 6 is no longer compatible with Fido? Did your receive an error or notice to that effect? I understand the iPhone 6 is no longer receiving iOS updates (see here). However, the device should still have compatible bands/frequencies:
LTE bands: 1 (2100 MHz), 2 (1900 MHz), 3 (1800 MHz), 4 (AWS), 5 (850 MHz), 7 (2600 MHz), 8 (900 MHz), 13 (700c MHz), 17 (700b MHz), 18 (800 MHz), 19 (800 MHz), 20 (800 DD), 25 (1900 MHz), 26 (800 MHz), 28 (700 APT MHz) and 29 (700 de MHz). Besides, the GSM version also works on UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz) and GSM/EDGE (850, 900, 1800, 1900 MHz). ~ taken from here.
Hope this helps 😀
Cheers
