Sony released patch 1.01 last night, but even after downloading it, gamers - particularly, it seems, in the UK - are still noting problems this evening.
However, Naughty Dog has just promised that help is at hand. Studio boss Christophe Balestra wrote on Twitter:
"We [have] found a problem with matchmaking a couple of hours ago and a fix is on its way. Today will be a better day. Thanks for your support :)"