I’ve had similar issues, only with the PMDG 737-7. I love the aircraft, but it only seems to CTD on longer flights. I tried flying from KMDW(Chicago) to KLAX and it crashed about 10 mins into my descent. However on shorter flights there’s no issues.
The only 3rd party add on I was using was PACX, and I confirmed my internet and pc didn’t have any issues.
What’s strange is I’ve taken the 747 on numerous flights that are 6+ hours with the same add-ons and pc/internet settings and never had any CTD’s. I hope this is something that can be addressed.