The main issue reported in this thread is now resolved, so I'll unsticky it and close it.
@Feloxy0 Hey, your friend can try opening the ports listed on this page: https://help.ea.com/en-us/help/battlefield/battlefield-1/battlefield-1-troubleshooting
There's also further troubleshooting on this page: https://help.ea.com/en/help/faq/connection-troubleshooting-basic/
@TheUltraPixel Your account is prevented from playing at this time. Please reach out to support to have this looked into.