It's been a long time since I've played with DD-WRT (over a decade), do you recall where the setting is to only allow log in via cat5?
Wireless> Advanced settings.
Bandwidth is a big issue, but my needs are low. Also early AM most everybody is still in bed. But getting a stable connection is step 1.
We just got back from 2 weeks up north, 5 days at Aune Osborn and 4 at Mackinaw Mill Creek. Then back home where it's still upper 90's
Used this setup both places.