The immigration issue has been frustrating for everyone including Trump, but look at it politically...... it is likely the main motivator for most of his voters and it is one of the major drivers for crossover votes among democrats.
While I believe Trump truly wants to fix it and there is no doubt he wants to secure the border, the longer it drags out the better it is for him politically. He robbed the rats of the DACA issue in a brilliant move by backing them into a corner and they have stayed there pouting ever since.
Any wall as such won’t fly. A great security system might.
I am not totally sure — they screamed him into some concessions on the “separated families” issue. His Christian support was threatening to bolt.