I Cannot send pictures with MMS since Pie update

I have a Samsung S8+ I cannot send pictures with MMS since the Pie update months ago.  Can someone please help!  A little history....I live in a town where Comcast has contracted to use local towers (Bluegrass Cellular towers).  We are not on a Verizon tower...the nearest Verizon tower is 40 miles away.  Comcast sells phones to customers in our area and is due to open a mobile store in our town on November 2nd.

When I am 40 miles away and using a Verizon tower my phone works perfectly.  I always keep my WiFI and Mobile data turned on and have no problems sending picures with MMS.  When I am in my home town (using Bluegrass Cellular towers) no matter what messaging app I use I cannot send pictures with MMS 90% of the time.  Every now and then I can get one to go out.  I've reached out to Xfinity customer service several times and they have told me they cannot help me because I am not on a Verizon tower.  They refuse to escalate my issue any further or continue to help me (because I am not on a Verizon tower). 

I've been told to use a different messaging app.  I've tried several apps and this does not fix the problem.  

Please help!