I meet Vietnamese people who have been here for years and are still lonely. Not connected to the local community, circulating within a small Vietnamese one that has its own share of drama. And every year, the only thing they look forward to is going home.
The reasons are not complicated. There are two.
One: the language ceiling
If you learned English only to qualify to come here, or learned it after arriving in order to regularise your status, your English usually stops at basic transactional level: greetings, filling up the car, renting a flat.
It never gets past that into talking about anything with depth.
Two: conversation is its own skill
And this is the important part: 6.5 or 7.0 does not automatically connect you to anyone.
Communicating is not only English. It is knowing how to start a conversation, how to keep one going, how to make the other person comfortable.
If you already found conversation difficult at home, at least it was in Vietnamese and you could manage. Here you are short on the English and short on the conversational skill at the same time, which is twice as hard.
Why it helps to separate them
Because if you only fix one, you will be disappointed.
People reach 7.0, find themselves still lonely, and conclude English did not help. English did its part. What remains is a different skill, and that one can also be learned.