There are always trouble at start of UAC.
Simply because the event starts at same time for all kingdoms.
And most of all top 10 alliances join the campaign.
While KvK only top 2 alliances mostly join that campaign.
As I see it there are 2 ways to overcome that issue .
1. If GoG where to add another server to their loadbalancer.
Because factually with letting the event start at same time for all kingdoms they are performing a DDOS on themselfs.
2. Simply split the event in 2.
Like they did with KE.
1 kingdom has KE together with KvK and other kingdom has KE with UAC.
So they could in fact do UAC in 1 kingom during KVK and other during KE.
And split it in 2,
That would take the load of the servers at the start.
And giving those servers a little bit more room.