We use Web.Config RestricttoIPs on the Per Page settings. It needs an option to be able to Resolve Domain Names instead of just IP addresses. This would allow us to deal with traffic coming from dynamic IP sources.
Just want to add these 2 threads are slightly different. One is restrict to IPs, where as the other one is the end-point connecting back to the cloudhosted environment. Different vendors block all unknown traffic, so our IT Teams can't connect to these users because your cloudhosted IPs change too frequently to get them to update whitelist's all the time.
The client installed on our windows end points are attempting to call back via the IP address assigned to our instance(the relay's IP), instead of the relay FQDN. Because of this, we are forced to whitelist the IP, which changes anytime there's an update or we change hosting locations or just randomly (when ConnectWise updates their servers?).
This makes ConnectWise unusable in a secure whitelist only environment or for IT Teams that support multiple different clients each with their own whitelisting required.