What is the best way of securely setting up my 2011UiAS to host a very small (and and low traffic) web site? I have static IP.
It's small and has like 5-10 visits a day. We have two computers connected at all the times, but would the built-in USB be more secure? Putting the 2-3MB website on a USB stick and mount this?
Too bad you have a 2011 that cannot run "containers" , that is a MIPS platform, you need ARM/ARM64/x64 for containers.
Otherwise that would have been your best option.
You also might want to experiment with the "proxy" feature of RouterOS, but make changes to all your webpages (Cache-Control directives) but I'm afraid the maximum value is 604800 (= 7 days) then any proxy will flush it and re-fetch it from the origin. If you manage to get ALL the "objects" of you small website in the cache and serve only from the cache ... you "kind of" have some webserver but I have my doubts if it will work in practice. A very,very simple website only with some static ojects might work but....
So besides this I have no ideas how to accomplish this. You cannot "use" the webservice on RouterOS that serves "Webfig" for these purposes. That would be a complete security loophole. I don't think you can "serve" other files than webfig and you do not have access to these files from RouterOS I believe.