Have those been modem or router resyncs?
Best to leave the modem well alone; it's sync speed will increase automatically when (and only when) DLM permits.
Too may resets and DLM may lower your speed.
What is needed is a router
PPPoE disconnect/reconnect; to force the IP profile to match the sync speed.
As Chrysalis says, if you have an unlocked modem, you will know when it is worth disconnect/reconnecting the router.
However, too much router disconnect/reconnecting or resetting won't do any harm.
Moved (with trepidation turned relief) to BT Infinity 2 for upload speed. Happy BE user for several years.