With Instant AP it is strongly recommended to use a separate VLAN, which goes untagged to the AP ports, for management and clustering traffic, including communication to Airwave. If VLAN50 now just holds your controller based campus APs, and no clients or other wired devices, you can perfectly reuse that VLAN for the Instant management.
Then your clients should go in separate VLAN/VLANs that should be tagged to the same ports that the APs connect to.
One approach that would work if you will use the same ports to connect to the APs (or even the same APs if they can be converted):
- First test with a single AP untagged VLAN 50, tagged with your client VLANs.
- If you have already separate client VLANs, you can keep it the same.
- If the single AP works, configure your AP ports to have VLAN50 untagged and your client VLANs tagged.
- Make sure that clients still can connect. Expect poor roaming behavior when you have both the controller APs and IAPs active in the same area.
- Add/replace with the new IAPs till all old APs are gone.
- Try to keep mixed areas with IAP/AP minimized, roaming will be poor.
If you can't keep the client VLANs the same, even further reduce the replacement time. Clients that are steady and connected should not so much be affected until you unplug the AP they are connected and roam to a different AP.