I’ve got 6 wordpress sites using Cloudlare, I have the cloudflare plugin installed and all the sites have been working fine for months. Recently I’ve had a problem which isn’t connected to cloudlare but struggling to fix it this got me thinking should the admin area of wordpress be cached? I put in a page filter domain.com/wp-admin/* but that seemed to have no effect
Have a look at the post below and make sure the Page Rule is at the top. Then create Firewall rules to restrict access to the backend. If you can limit acceess to a single IP if not, AS, Country etc.
No. It should not be cached by neither Cloudflare, nor the origin server.
The post @Withheld has mentioned has some page rules with the specific intent of NOT caching /wp-admin/, while caching everything in the front end of your website. And these rules should not affect how Cloudflare handles css, js, image and other static files, which are cached by default. They will only make your website faster by caching the generated HTML pages of your website.
Having said that, as you mentioned problems unrelated to Cloudflare, you will have to assess whether caching the generated HTML is the appropriate solution given the issues you are facing. You can always try and see if it helps.