Are the other cameras connected to the same cell? IE: LAC and CellID are the same? Cellular data throughput can vary wildly between cells depending on the backhaul and tower saturation so it could simply be that the tower this particular node is connected to is experiencing saturation issues and reducing the available bandwidth. If you’re able to run some ping tests from the various GXs, that may shed some light on the issue as well. You’d also want to confirm that the local LAN connection from the IP Camera to the GX is solid. Look for any Ethernet statistics on the IP Camera and the GX, checking for speed/duplex mismatches or CRC errors. Confirm both devices are configured for Auto or force both sides to static Ethernet configs and if CRC is incrementing, could be a bad cable/poor contacts.
Cheers,
Adam