Fleaky telemetry connection with Doodle labs modem

[Aaky]

Hello,
We are working on VOXL2 with SDK 1.1.2 and have built a custom drone which has Doodle labs modem installed for communication purpose.
I am facing problems with SDK 1.1.2 specifically with telemetry of PX4 with GCS being very fleaky and keeps connecting/disconnecting.

I was previously working on SDK 0.9.5 where I didnt saw any problem. I also went through certain posts over forum which suggested to set "udp_mtu" to higher value for Doodle labs modem related radios in voxl-mavlink-server. I did this and have set udp_mtu to 500. There was parameter loading problem which got solved with this setup but communication is very fleaky still.
I also verified if radios are able to communicate with each other when VOXL disconnects with GCS, here I saw modems were able to ping each other without any problems and it was just VOXL which was having tough time connecting to GCS. I have even seen, the Ethernet interface which comes up with Doodle USB connection going on-off at times, probably leading to disconnections. Maybe its hardware problem which we are looking into, We have connected D+,D- and GND of Doodle radio with Microhard Add-on board's USB connector over VOXL2.
Please help me ahead if there are any clues in solving this problem since with same connections on SDK 0.9.5 communcation was absolutely solid.