cox not send or receives some mails form/ to Germany

cox since a couple of weeks does not send or receives some mails form/ to Germany (have not tried other countries)
- not all, so one can not know which do not go/ come through.

I have not changed my settings, nor updated my provider?

Cox what is your problem? There were issues with mails when I was abroad but that was 2017 and 2018 but not 2019. Now this mess.

Please solve this issue asap!