I’ve had this for some weeks. It’s the TTb backhaul as the delay is between my end and and Zen, in my case. Zen can’t and won’t be able to address this issue
Your right, I phoned up Zen today and explained the situation about the Gateways and we both agreed that there is PoP issue, And yes i was moved onto talktalk wholesale line in May 2021 but when i first joined Zen i was on BT WBC even though on samknows Zen has there own LLU at exchange?
EDIT
Zen is aware of the issue between TT and have asked TT for a fix. Now is the waiting game.