I can access to https://www.dropboxforum.com without any issue but can't do so to https://www.dropbox.com (unless I utilize a VPN or Proxy IP, as it turned out). This issue only occurs on but one of my multiple machines in the same LAN. The other machines have the exact same settings (I duplicate my OSs leaving just Machine ID unique to each machine) do not experience this issue. Also, (I have checked that) this issue does not happen with my other cloud providers (only DropBox and only on my primary machine). Is this related to this one Machine ID?
Also, prior to this issue, I was running Air Explorer to sync my clouds (on this machine). Since this issue, now Air Explorer just endlessly waits for Read/Write permission by DropBox (when infact, DropBox has already given it).
I have done: uninstall DropBox Desktop & AIr Explorer, delete all traces of Network Card Drivers, release&renew IPV4&IPV6, flush®ister DNS, remove all traces of VPNs and Proxy IPs, disable Firewall, clear Browser, turn-off Browser DNS-over-HTTPS, install&utilize another browser with different User-Agent Credential, try utilizing multiple (free) DNS Servers, checked that my other machines connect to https://www.dropbox.com without problem.
Still (no luck), I get www.dropbox.com refused to connect. ... ERR_CONNECTION_REFUSED on just this one machine.
+ Also I notice: Share Links of media files (in DropBox) onto a website via various embed methods (with ?dl=0 changed to ?dl=1, ?raw=0, ?raw=1) do not work (I get "You do not seem to belong here, please Log-In...." or something or rather) while I have allowed anyone with the link to view the file without expiration date and with permision to download. Is this related to the preceding issue of connection to https://www.dropbox.com?
Hello Walter, thank you for your input. I think so, Network/Security Settings is the case.
I was starting-up BetterNet VPN to authenticate myself for DropBox, BetterNet VPN was refused connection and stated "Please repair this application". So the issue is not isolated to DropBox.
I think it is caused by (Host) Trust/Authentication Settings on one of my Optimization Softwares (I am running a few of those). I should check them one-by-one, but am pressed for time. I will do an OS clean install instead and trace my Softwares installation procedure (see where this issue began).
I will update you, in a couple of days, once I complete my installs.