Outlook and xfinitytyahoo email delays

I use desktop outlook. Ever since xfinity switched to yahoo, I have times when everything works fine (send & receives) .  But every so often I won't receive new emails for hours (or days).  Even if I press send/receive. Sending works fine,  receiving doesn't. I get no errors,  and if I use yahoo's web mail,  I see the new emails out there.   Then it will suddenly start working again. 

I have tried all the usual stuff,  updated server settings, created an app password,  cleared credentials,  re-added the account, deleting the old .pst file,  etc. 

After re-adding everything, outlook spends time rebuilding all the files from the yahoo imap servers.  And things will work on for a while.   Sending emails always works,  it is just receiving that "hibernates for hours.  Again no errors,  and it will suddenly start to work again without doing anything.  (Yahoo webmail and my phone function normally) 

Again this wasn't an issue the whole time we were using the xfinity email servers. 

Help!