Just wondered if I may have solved a part of this website stumbling issue.
I turned off "SIP ALG status" under "Security" SIP ALG settings in the router. (By default its switched to the ON position)
Apparently its a NAT tool that inspects SIP Messages and transforms the Private IP addresses and Ports to Public IP Addresses and Ports. So its certainly possible that SIP messages could be slowing down the request/response process.
May be a complete coincidence but since turning it off the problem has vanished for me.
Edited by buggerlugs (Thu 16-Apr-20 10:34:58)