Recently I had upgraded Root cert server OS ver from 2012 to 2019 via in place upgrade. Yes, I know it is not the most ideal way but I had my reasons 🙂
After upgrade none of the help desk staff was was able to connect to root cert server via MMC or none of the PC was able to request certs. So everyone was in help desk wasn’t happy 😦 But user was able to request certs and domain admin was able to connect to cert MMC and issue them. Since the PC wasn’t able to request any certs and end up in breaking SCCM communication which was done via PKI. So error I was getting was this,
After many search one of the post from here save the day and it was issue with DCOM error caused by the in place upgrade, how? I have no idea 🙂 https://theitbros.com/the-rpc-server-is-unavailable-0x800706ba/
Solution was this in my case,
In the AD search for Certificate Service DCOM Access and add Domain computers/Users/domain controllers as members
Then go to root CA server and run in cmd in admin mode.
certutil -setreg SetupStatus -SETUP_DCOM_SECURITY_UPDATED_FLAG net stop certsvc & net start certsvc
After this I was able to resolved my issue.
NetSideTech 
I have the same issue, but did not work
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I have the sam issue, but did not work
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May be referrer to the original post that I linked in the article. Unfortunately I cannot test this again, since cert server is live.
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