I don't think our connection is very good. Let me call you back.
Our connection is bad/poor. Why don't I hang up once and call you again?
この場合、次のような言い方ができますよ。
ーI don't think our connection is very good. Let me call you back.
「接続があまり良くないようなので、かけ直させてください」
one's connection is not very good で「接続が悪い」と言えます。
to call back で「かけ直す」
ーOur connection is bad/poor. Why don't I hang up once and call you again?
「接続が悪いので、一度切ってからもう一度かけますね」
one's connection is bad/poor で「接続が悪い」とも言えます。
to hang up で「電話を切る」
ご参考まで!