Can you enter your phone number and post results remember delete number https://www.btwholesale.com/includes/adsl/adsl.htm
can you post post stats from your hub. Go to advanced settings and then technical log information
you our need to test your speed with a wired connection not wireless
this may help with image https://community.bt.com/t5/help/faqpage/faq-category-id/images#images
you can conenct hub to pc whether pc is on or off. having hub that close to all the electrical equipment might cause a problem but only by trying will you know for sure
Don't know who told you you have too many wireless things and a wireless extender kit would fix it but they clearly are clueless so best ignored. So is whoever told you not to change wireless channel.