Problem with watchdog timer on mt7688an related to LEDE 17.01

I have a problem with watchdog timer on Hlk7688an module related to LEDE 17.01. when I test watchdog timer manually, it seems watchdog is not working. I changed mt7628an.dtsi file according below link :

But now when I test watchdog timer manually again, my device (modem router)crashed after watchdog timer finishing instead of device rebooting.
This problem is solved on Openwrt 18 and Openwrt 19 version,but because of some reasons (for example: very high load average in Openwrt 18 and Openwrt 19 version ) I have to use from LEDE 17.01 version.
I would be thankful if you guide me in this way and give me your solutions.

Probably best to see if there is a load problem at all, then, if so resolve that, as v17 is no longer supported.

Do you mean I working on openwrt 19?
Do you know high load average in version 18/19 is related to kernel version?
my CPU is mt7688an , it has 1 core with 588MHz clock.