WordPress/PHP Expert Needed – Fix Changes Reverting, REST/API & Admin Issues

I’m battling an aggravating situation on my WordPress/Divi site: changes I make in the builder, plugin updates and some dashboard settings appear to save and then quietly roll back. Activating or deactivating plugins can also fail. The live website is also reporting an error, and I have had an issue with the cookie banner disappearing, so I would like the overall WordPress installation checked rather than treating this as only a Divi problem. SiteGround has investigated and found application-level 403 responses involving Divi and Jetpack. ModSecurity was checked and was not identified as the cause, and Cloudflare Development Mode made no difference. What you’ll encounter Divi changes that don’t persist Plugin updates and settings that revert Plugin activation/deactivation failures, sometimes returning “The link you followed has expired” REST/API-related 403 responses An error reported on the live website Cookie banner/functionality issues Several caching layers: Cloudflare, SiteGround Optimiser and Divi CSS caching A useful controlled test on staging: I added TEST124 in Divi. The Divi sync-to-server request returned 200 OK, contained TEST124 in the payload, and returned save_verification: true. After reloading, TEST124 had disappeared. Scope of work Replicate the problems and identify the underlying cause, including database, filesystem, permissions, REST/API, authentication/nonces and caching. Audit all installed plugins for duplicates, obsolete or unnecessary plugins and conflicts. Nothing should be removed until the site is stable. Review WordPress, Divi, Wordfence, Jetpack, SiteGround Optimiser, Cloudflare and REST/security settings. Check and correctly configure the different caching layers so they work together rather than interfering with WordPress writes. Check the live-site error and investigate why the cookie banner/functionality has disappeared. Once stable, safely remove genuinely unnecessary plugins. Provide a short handover explaining what was fixed, what was removed and the final configuration. Acceptance criteria Divi edits persist after repeated save/reload tests. Plugin updates and activation/deactivation work normally. WordPress dashboard settings remain changed. The live-site error is resolved. The cookie banner/functionality is working correctly. No relevant new 403/500 or permission errors appear in the logs. Cloudflare, SiteGround Optimiser and Divi caching are correctly configured. Any removed plugins have a clear justification. I can provide administrator access and, if genuinely required, SSH access. Creating a new administrator has also caused problems. The administrator invitation/confirmation email was received successfully, but the new administrator was then blocked at the 2FA stage. Before starting substantial work, please confirm your estimated hours/cost and let me know before exceeding the agreed amount.