Hi Han Vertegaal,
I figured out this issue.
You need to change the file eagle.app.v6.ld
It is on the folder ld of your choosen SDK (RTOS or NOOS)
Choose line 29 to: irom0_0_seg : org = 0x40210000, len = 0x5C000
Of course you can try another numbers, but look in the documentation (ESP8266 FOTA Introduction) for more information
Good luck
Chees