Not sure it's necessarily connected to the merger. I have Three 5G broadband and, yes, about the same time as the merger I've been having terrible problems connecting to some websites and terrible lag on certain services. This is most noticeable with a game I play but I'm also getting frequent disconnects and timeouts from sites like Bluesky and Threads. However, and this is the clue, if I use a VPN it works fine. I also have a phone which used the Vodafone 5G network and a hotspot on that also works fine.
I think that there's either a badly configured network or Three have a peer agreement with another ISP that has a badly configured network, but as I have a workaround I can't justify spending an hour on the phone (which is what it took last time on a similar problem) to fix it.
Just for funsies, I've attached a trace of a "direct" connection with Three 5G to the game I play, and one via a VPN. I should add that other players across Europe are also reporting problems connecting with this game.
