Possible QoS Fault

I use a media PC to stream TV channels. Up until CU 174 that worked without problem.

CU 175 & 176 introduce an unworkable delay, which results in repetitive breaks in streaming. Zoom audio out also became erratic, although video & audio in are acceptable.

I am in a locality with poor Internet infrastructure - 55 yo telephone pairs to a fiber node, operating VDSL2. I can generally get 5 Mb/s or better download but never better than 1 Mb/s upload.

I have not attempted to tune QoS, because I am uncertain what mode those two services use.

Is anyone else having QoS problems, or is it simply my poor Internet ?