no longer can access omv 4.x server via webUI

Hi,

I received an email regarding let's encrypt cert expiry notice this evening, soＩlogin to my omv as usual and click renew in letsencrypt plugin. It failed to do so... something to do with connection, I tried to turn off forced SSL connection box and then retry but a error warning message kept popping up.... so I tried to turn off ssl/tlc connection all together but when I check my cert in let's encrypt, it's gone!

Starting from that moment, I can no longer get access to WEBUI page,

This site can’t be reached
192.168.0.xxx refused to connect.

i reset GUI configuration in omv-firstaid but the page is still inaccessible. all my other plugins as well as transmission are accessible, though.
I uninstalled let's encrypt in putty using command line, still no luck.

Any advise will be greatly appreciated.

thanks for your reply, i will give it a shot later today and see what happen.
The plugin in is in OMV repo, i assumed it to be working properly...
next time I will try docker version.