There have been many posts on here stating that since the switch from Virgin/EE to Virgin/Vodafone customers have seen a significant decrease in data speeds.
I am the same - my rural location could achieve speeds of 60mbs with EE but that went to around 6mbs with Vodafone. As such I decided to bite the bullet and switch from Ooomph to Volt which means a change from Vodafone to O2,
I use an Archer router to install my SIM in which is connected to a directional 4G aerial. All the above speeds were achieved with the above configuration. Yes I know technically I may be in breach of the t&c's regarding fair use policy but I would argue whats the difference between streaming Netflix via this configuration and tethering to a mobile phone. And the mobile signal is poor anyway. I am no where near the data limit of the 'unlimited' package either..
Anyway over the weekend I switched to the O2 SIM. Result - speeds on kbs rather than mbs!. Oh dear, bring back Vodafone all is forgiven.
Anyway after moving the aerial 90 degrees and also locking it on a specific band (Band 1 for some strange reason) I now have much better data speeds of around 18mbs. No where near Virgin/EE of course but an improvement on Virgin/Vodafone.
But not sure this would be the answer for everyone having similar Virgin/Vodafone speed issues as I do use an router/aerial to gain better signal but I thought I would share my results with people.
My longer term plan (July) is to terminate my current 3 contract I have with my mobile, switch to EE and then use the Virgin/O2 SIM in that.