I have a Telsys CPL4
Not really sure what version was loaded before i updated, first time updating it since i bought it.
I updated because it suddenly started rebooting itself a couple of times a day for no reason.
I've tried all the options you mentioned, but downloads still kill everything else.
I even ran a speedtest which gave me 38/51, so nothing wrong there.
Tried downloading something from Steam and even that causes problems.