Advice needed on my current setup

So I have a D-Link DIR-885L with openwrt flash for a few years now with no problems. Recently, I had to change my Internet providers and switch to their 4G wireless broadband which came with a Huawei B618 - 65d, but the WiFi range on it was horrible so I disable it's WiFi and bridge (LAN) it to the DIR-88L(which acts as the only WiFi network). So my first question is if this is the right way to do it? And the second question, can I enable SQM on the DIR-885L? If yes, what are the correct configuration for it? Thanks in advance.

If you want to use the DIR-885L only as Access Point, then follow the dumbAP guide.
For SQM I am not sure if there is a point to use it on the dumbAP.