Modem performance on coverage edges

I am wondering if modem connectivity in situations where coverage is on the edge of another coverage area is being looked at. In those situations I just don’t have any connection at all. It makes it so that I have to use tethering with another device to get internet on the phone. I would really like it if my cellular data connection could work in these situations. I’m along the Dutch and German borders if that matters.

Just out of curiosity: is roaming enabled?

Yes it is. I’m on Aldi Talk, which could be the issue, but in my fairphone the sim is able to maintain a data connection.