I am on M600 and haven't had any issues for a year. Yesterday I noticed browsing became a little sluggish and did a speed test which showed my upload speed to be super slow and is still slow this morning.
I've turned off my home hub 3 for 10-15mins and turned it back on but it hasn't made any difference.
I've checked for faults online and on the phone but there aren't any reported in my area.
Can you post your Hub status and logs? Someone should be spot if there is a problem Navigate to http://192.168.0.1 (or http://192.168.100.1 - if in modem mode) Don't log in! Click on 'router status' Copy/paste the data from each of the tabs. The forum software will remove the MAC addresses for you (you may need to click the 'post' button again).
Also, set up a 'Broadband Quality Monitor'. This will monitor the state of your connection and record any network dropouts etc - You can do this at ThinkBroadband (https://www.thinkbroadband.com/broadband/monitoring/quality) Give it a while to gather data and then click 'Share Live graph' and paste the 'Direct Link' into the forum!
Thanks for posting on the Community Forums. I'm sorry to hear you've been suffering from slow broadband speeds recently.
As @lotharmat has correctly advised, there are a few issues here with your T3 timeouts which will need looking into by an engineer. I'm going to pop you over a PM now so I can take some more details and get this arranged for you.
Please look out for my message over at the purple envelope.