Mvebu wrt3200acm - kernel version

just noticed that the default kernel version has changed from 4.9 to 4.14 ? why downgrade? how can I go back to 4.9

Kernel 4.14 is newer than kernel 4.9.

kernel.org

The version numbers can be misunderstood... actually 14 means "fourteen", which is higher than 9 (nine), thus newer.