I noticed recently that my PC was taking approximately 10-15 seconds to register a logical network connection after booting Windows 10. Initially, I thought this might have been something to do with Spanning Tree but then realised that the delay didn’t match RSTP timers.
After much messing around, I came to the conclusion that the problem was being caused by one of the PCAP drivers associated with Wireshark that I had installed a few weeks ago and forgotten about.
Removing Wireshark and the PCAP driver resolved the problem.