Juz finished multiple approach on getting firmware v1.21 to stabilize on my DIR-655 but failed.
The wireless module of DIR-655 would just drop off and restart itself whenever saving settings and sometimes even with just adding values such as inbound filter rules.
Even tried reset to factory defaults, just plain setup from scratch to my environment. Even clicking of save settings result in DWA-142 losing wireless connection which is due to the wireless module of DIR-655 restarting (based on the logs).
Revert back to firmware 1.20 and everything stabilize.