DNP Master not communicating after virtual ip address switchover of DNP slave

I don't have much networking experience and this isn't my area of expertise so forgive me if I'm not very verbose and don't explain too well.

I'm attempting to send DNP communications from a redundant RTU (basically a middleman between field devices and our DNP system) setup to our DNP master system. The redundancy for these RTUs utilizes a virtual address that switches over when the primary fails. The DNP master system is setup to be polling the virtual address.

The problem is our DNP master system (which is not my department) doesn't seem to accept communication from the virtual address anymore when an RTU fail-over occurs (backup unit becomes active). I previously tested the RTU with a DNP SCADA test box and saw no issue on fail-over. I also see the RTU working fine on my end sending data through the virtual address. The DNP master system just seems to stop all communication with the RTUs virtual address.

Any tips on troubleshooting this and what might be wrong? Monday I'm planning on doing some wireshark analysation. I'm not a network guy I'm a software guy so I'm somewhat helpless here lol, hoping to learn more from this experience.