Overlay Synchronization

I wrote an Arduino program to send dynamic text overlays to ENC1-V3 (according to the API protocol *). It’s working well, except that the overlay update sometimes displays a character jump when updating. This usually occurs when the update is asynchronous with the frame rate. Is there a way to synchronize this by making the update be done in the vertical interval ? Perhaps a firmware correction ? Or a custom firmware? (Obs. This does not occur with the timestamp overlay indicating that are possible some kind of syncronization) *P.S. I have also tested using the HTTP Request: POST /RPC HTTP/1.1 method as used in the Ethernet Interface server page, but the results were the same.