doremiqc on "All admin options work fine on mobile, but not on PC"

(Theme Twenty Fourteen)
I tried to check everything, plugins, theme, etc. Most options on wp-admin are hit or miss on PC, most of time things go loading forever until it goes to a blank screen, usually timeout. Media usually leads to http error. However, I tried the same options on my phone and it just works fine and loads quickly. I read it could be related to firewall, but I'm not tech savvy. Any tips?
Memory on wp-config is set to 128mb. I also contacted the host but they can't find any issues and as I said everything seems to work fine on mobile. The website itself works fine on PC, trouble only occurs for admin options, editing menus, saving drafts, publishing, uploading media, etc. This happens in both browsers, chrome and edge.