Charles Spurgeon Commentary 1 Corinthians 11:20

"When therefore ye assemble yourselves together, it is not possible to eat the Lord`s supper:" — 1 Corinthians 11:20 (ASV)

When you come together therefore into one place, this is not to eat the Lord's supper.

Merely meeting together, each person bringing his or her own portion of bread and wine, and each one eating the provided portion, was not celebrating the Lord's supper.