I want my untagged default production VLAN and a Tagged VLAN 99 to be transmitted over my MR66's. I turned on the Tagging and it knocked my untagged VLAN out.
How can I make them co-exist?
Right, but on the Meraki, I went to add the Tagged VLAN and it knocked the Untagged one out. How can I add the tagged leaving the other one alone? I looked around in the interface...didn't see an option. On switches you can have both Untagged and Tagged VLAN's on the same port.
Yes. One tagged, one not. Both VLAN's going to a Cisco WAP371 that separate them into two SSIDs. One tagged one not.
I just need to broadcast them thru the Meraki's.
(The untagged is simply the default VLAN. I added the Tagged one to send that traffic to a guest network/ISP.)
Are you using the MR66's as a bridge pair? If so, they only support one VLAN I do believe, please see below
Look at ethernet bridging section