My Unemployability dates changed

[duffman88]

I was awarded Unemployability total and permanent And effective date of November 4 and now there saying my effective date is April 20 what does it mean and why would they change it? The only thing I see is where it states I am permanent and total the date changed but where it says last time changed to award has same date as before 

[Berta]

When you get the actual decision, it will tell more as to the EED.

Do you get SSDI solely for your Service connected disability(ies)?

If so could the April date (2019) compare to the SSDI date of total disability?