Hello and welcome @denismile

After you joined in the what? The main world?
If that happens try decreasing your render distance before joining and when you loaded the server resourcepack you should be able to increase it again to the normal amount you use.

If that doesn't work try disabeling your server resourcepacks by clicking the server and going to edit and then putting the server resourecpacks on disabled. Then you can download our packs in the resources section on the forums and switch them manually for each region. (We use different resourcepacks for different regions of middle earth, eg Gondor, Rohan, Eriador...)