I cannot afford to set up a testserver environment, but I need an environment, to test my live site on. Would it make sense to make a setup like this:
Live site: https://example.com
Dev site : https://dev.example.com
Would the dev site interfere with the live site? Would it slow down the live site, SEO and so on? Is this bad standard to do?
Best Regards
Yes you can have the above setup:
Would the dev site interfere with the live site?
If it uses its own folder and database it won't interfere with live website
Would it slow down the live site, SEO and so on?
It will use up some resources on server may or may not slow down the website.
Update your robots.txt to disable your test site being crawled by search engine bots
Is this bad standard to do?
Normal its done on separate servers with identical config. Though itz fair enough to setup on same server.