You must do a reset to factory defaults and manually enter the minimum required settings to get connected to your ISP and your client. I would suggest a different ssid be used too.
To be clear, I'm not trying to do the same thing as the OP. If I wanted to do what the OP wants, I wouldn't be that hard. I'd just have to put my device in router mode, set up the 2.4Ghz radio with a certain SSID and password, then switch into media bridge mode.
On the newest Merlin builds, I'm pretty sure I'd end up with a bridge over the 5Ghz radio, and an AP on the 2.4 Ghz radio.
But, that's not what I want. I want to shut off the 2.4 radio entirely when I'm in media bridge mode. I can't do that either in the newest merlin builds or in the john9527 fork.
In the john9527 builds, 2.4 radio kind of shuts off. When I use wifi scanning tools I see weak a weak, hidden 2.4Ghz AP when my media bridge is on. I can't get anything to connect to it, but that might just be a client limitation (I tried manually entering the SSID and password, but that was still a no-go on a Win7 laptop, an Android phone, and a Surface RT).
I tried a factory reset- both on the merlin builds and on the john9527 builds. That didn't change anything. And I found
a post by RMerlin that seems to confirm the bug.