For the last day or so, my Realm has been experiencing huge amounts of lag. Chunks will fail to load properly, resulting in invisible sections with caves below visible. Chests and doors will take several seconds to register interaction. Travelling through a nether portal can take more than 2 minutes to 'build the terrain'. Players experience random damage coming from who knows what.

As mentioned in the title, we have several players from different regions (mainly Australia and Canada) and they are all experiencing this lag.

Sometimes, it is possible to get at least the local world to become responsive enough to interact and play, but it is impossible to travel any reasonable distance without re-logging several times to compensate for unloaded chunks.

Sleeping does seem to help 'refresh' the world and improve the lag, but it only ever varies from 'moderate' to 'severe'.

Regarding the attached video
My aim with this video was to show the lag when travelling via rails in the nether, which is one of the places where the lag is most obvious. Instead, I managed to capture chunks not loading properly as well as clipping through the floor - the end of this rail is completely enclosed and there should be no way that I ended up where I did.