lag and buffering

hi guys I could really us some assistance here. I have a nexbox A95x. Ive nusigKodi on th e box for some time now with no issus. al of a suden im getting serious lag and loads of buffering. Im connected via a wifi LTE router with average download of 20MBS. I took the box to test on another router at a different location. I connected to an ADSL Router on a 5 MBPS line and plyed back without issue. any ideas what could be the issue?