Oldweb is right: the issue about "page not found" is due to this Forum's software - that section is broke for non-logged in users. This is what you SHOULD be getting by clicking on a link in a thread:
And clicking on the "Continue to External Link" takes you to the actual web page.
If you look at the URL you will see it is properly formatted after the "&external_page=" area;
...
https://www.thorforums.com/forums/mi...threadid=27332&external_page=https://www.amazon.com/DC-HOUSE-Upgr...dp/B08LVKCZPY/...
But, the forum hashes the link substituting ascii code for non-alphanumeric characters so what you get is:
...
https://www.thorforums.com/forums/mi...VKCZPY%2Fref%3...
So instead of
https:// you get
https%3A%2F%2F which gets you the "page not found" error.
So it may be broke due to an actual problem in the software, or it may be broke due to changes/advances in web browsers, but in either case it probably won't get fixed until the forum moves to newer software.