G6-a: Revision with coordinating conjunction
G6-aConsider separating the clauses with a comma and a coordinating conjunction.
There are seven coordinating conjunctions in English: and, but, or, nor, for, so, and yet. When a coordinating conjunction joins independent clauses, it is usually preceded by a comma. (See P1-a.)
However is a transitional expression, not a coordinating conjunction, so it cannot be used with only a comma to join independent clauses. (See also G6-b.)