You're never going to get Gigabit over wireless. The speeds quoted are very good and nothing is wrong with your setup. The Huawei HG659 is an incredibly good router.
router side is good for sure, but the hg659 wifi implementation is poor at best - both range and speed are terrible.
I put an amplifi afi-r in front of it in AP mode, and can now reliably hit 450-480mbs testing on the 5ghz band with a decent AC client, was expecting to have to go to a full amplifi mesh setup but the range on the afi-r is good enough even at the far end of the house (with the hg659b the signal there was marginal to non-existent)