18.06.1 hangs on large/fast downloads

I have a HooToo TM06 and have used OpenWRT (GL MT300 build) since 15 chaos calmer. It seems that with 18.06.1, large/fast file downloads stop shortly after starting (i can't even complete a speed test) and cause all other internet communication to cease until I restart either the WWAN or LAN interface from LUCI. This problem seems new to me. Nothing obvious in logs either (from LUCI). I am using wifi>wifi routing.

Regular internet browsing works fine until I need to download a large file.

Edit - I've just noticed this behavior also happens when using wired (WAN)>wifi routing, though it takes a bit longer to happen. I imagine i downloaded ~500mb before it happened this time. I also didn't have to restart any interface, I just resumed the download.

Any troubleshooting suggestions? Is this a known issue?

found this: https://github.com/openwrt/mt76/issues/169 and un-checked "Disassociate On Low Acknowledgement". Seems to help.