Entirely possible I'm completely missing something but I've recently purchased an MQS and it's behaving strangely and inconsistently, not sure if I'm an idiot or if I've got a dud unit.

First off: the use-case I bought it for was that I have an RB1100 900km away that I've done "the dumb" on and broken my access to (stuff inside can get out fine but I can't get in), my smart-hands on-site tried to access it via local ethernet in order to restore the config backup from before I broke it, but due to overzealous corporate policies their laptop refuses to talk to the DHCP server on it (they don't have permissions to set a static IP, and winbox can't see it via MAC discovery), so my plan was to send them an MQS, have them plug it into one of the management ethernet ports then connect to the wireless AP on the MQS and log in from their smart phone.

I assumed that to achieve this I'd just enable the DHCP client on the ETH interface then I'd connect to the wireless AP, and it'd just bridge the connection across, it did not.

When I originally received it I was unable to connect to the management interface from the wireless (and I seem to have intermittent issues connecting still, connection just times out), so I connected from a wired connection with a static IP to update the firmware and change the config.

On ONE occasion I connected it up and connected to the wireless and it appeared to have just straight up bridged ETH and WIFI, I got an IP from the internal DHCP server, but I've never been able to repeat that (in spite of several config resets and such)...

At this stage this is WAAAAAY too flaky to be usable for what I need it for, hopefully I'm just missing something?

(plan B is a custom payload on a sharkjack but I'd rather not go to the development effort and if it goes sideways I'm still screwed)

This may not be helpful but anyway...

A map will do most everything the mqs will do, but reliably and with routeros under it.
(Maybe also a hap ax lite could be used)

You could setup wireguard, and have it phone home.

One thought with the MQS is that devices these days don't like it if they don't get internet when connected to the wifi,
and will go looking elsewhere pretty quickly. Sometimes if you keep reconnecting them, they get the message and will stay connected.

Yeah, plan C is pulling the cAP Lite out of my garage and building it up as a bridge and shipping that up instead

Plan C it is.

I've been able to get the MQS to behave SLIGHTLY more consistently but it's still not robust enough that I trust it to work for my smart hands.

Grabbed the cAP Lite from the garage, setup basic AP/bridge also threw in a Wireguard tunnel to a VPS as a contingency