During recent evaluation of a range of APRS servers and TNCs, I have inspected APRS-IS records and my own server logs to identify possible anomalies caused by the equipment under test.
In that time I have found defective records caused by digi / iGates: VK2JMA-5, Vk2YGV-5, VKWUWP-2, VK2UWP-1, VK2MPJ-1,VK2ZEN-5, VK2AMW-1, VK2RHR-1, VK2LKH-1, VK2MB-1, VK2BEN-1.
The defects include corruption of the callsign part of packets, corruption of the info part of packets, excessive preamble, excessive deviation, failure to decode some signals, inordinate delay in forwarding packets (over half an hour), and configuration to handle nth hop packets where it causes more congestion than any other benefit.
I am convinced that the people implementing and operating these things do not evaluate their installation and monitor performance on an onging basis.
Compounding the problem, most do not have a readily available contact to hear of defects from other users.
Most defects flagged in aprs.fi’s raw packets display are caused by defective digis and iGates.