I was having similar issues, mate.
im with Virgin , and got a deal this year to upgrade my package to Fibre 500Mbps , cheaper than the package I was already on with them. ( was 300Mbps )
im pretty clueless about it all to be fair, and I thought as I’m now officially on a quicker speed my internet should vastly improve, however nothing changed, infact it was running slower if anything after the upgrade.
I contacted virgin, who kindly sent round an engineer to check.
Firstly, he told me to bin my old ‘ official virgin ‘ wifi repeater plug in, as he said that wasn’t doing anything.
I have an IP CCTV cheap cam off Amazon anchored to the side of our house, and it was forever dropping offline. ( It requires something like a minimum of 75% constant signal strength to maintain operation ). The repeater I had couldn’t cope with all our other gadgets, and the cctv was barely pulling 40% signal at the best of times, so was pretty much inoperable.
He told me to order these M4 tp-link Mesh system from Amazon. £99.00 for a three pack.
I was sceptical, and thought they are just another plug in, but it’s not only given me a strong signal throughout our whole house , it maintains a strong signal to run everything perfectly.
ps, they also do a Tp-link M5 mesh, which I’m guessing do an equally good job, but are very small in comparison.