SEP client reports "Not Avaliable" on SEPM

Hi,

Many of my SEP clients are reporting "not avaliable" on SEPM console, please do not suggest uninstall and reinstall or repair as there are too many clients to be done on.

Troubleshooting stes done:

1) Waited for clients to take new updates, it did does take new updates but still does not reflect on SEPM

2) topped SEPM service and SEPM web server services and then delted .tmp and .err from agentinfo folder and then delelted the client from the group still the client reports as "not avaliable"

What do i do to fix this issue other than repair and cleanwipe..

Client version is 12.1.2

SEPM version is 12.1.4