AT&T iPad plan on MC7455 with a W826-T. Dual yagis using 25ft LMR400 cabling.
A couple weeks ago:
Internet speeds dropped significantly (from 70-100mbps to 9-20mbps fluctuating wildly) and really poor ping quality overall. Goes from a normal 80ish, to anywhere north of 200-3000ms. This was right around the time we added on to my home, but the new space is not in direct path between antenna and tower. So seems odd.
I went up to inspect the cabling, and one of the antenna wires plastic cover/sheathing had a long crack down it. So, I've replaced the LMR 200 with LMR 400 cabling. This helped somewhat, but not significantly. Perhaps 10% overall.
Thinking that somehow the new room may have caused issues, I've raised my antenna pair up about 6 feet higher. I have not had time to fine tune it directionally, but it is fairly close to where it was and the problem seemingly remains.
The first image below is from my original EM7565 before it got toasted in a power surge. I replaced that modem with an MC7455 a while back and actually saw an *improvement* in both signal and speeds. Unfortunately I do not have an image from the 7455 after I initially installed it with good numbers.
Original 7565 results:

Current 7455 Results:


Is there any other possibility I should be looking at? It seems like I'm still getting MIMO, but it's just not the same. I'm not entirely sure where else to test other than moving the antennas around but I'm fairly confident they're close to where they were originally just higher.