Hi Bumpa, that message is characteric of a web application firewall (WAF). Sites use a WAF to deflect bot attacks, denials of service attacks, and other undesirable traffic.

Sometimes these blocks are temporary.

Sometimes add-ons modify requests in a way that looks suspicious to a WAF. It's also possible that if you are accessing the site through a VPN or proxy server, that the public IP address associated with your request is on a block list. Unfortunately, since the messages do not provide much information, the only way to figure out the source of the issue is to try with and without filters, add-ons, VPNs and proxies and see whether that makes any difference.

I turned the AVG secure VPN button off and then connected without trouble. Many thanks