Huge Linux Server Lag after upgrading to Unreal 5.3

Just finished upgrading our linux server to Unreal 5.3 from 4.6 and the server’s ping latency has gone up from 50-100 ms to 400-600+ms. All codes and everything is basically the same.

Any idea what happened? I know unreal 5 uses doubles instead of floats, but I don’t think it would cause this much latency spike. My server still has plenty to CPU and bandwidth left so I don’t think it’s because UE5 is too heavy.

Any idea how do I tweak the server network settings? I can’t see the document anywhere except a few parameter on each actor replications.