I just uploaded to Firmware v1.1.1 Build 20210723 Rel.64608 and it got worst, now download speeds are lower 100's out of 1K-Mpbs.

Same issue here with brand new TL-R605 Tow ISPs, one with 1000Mbps and a 200Mbs (backup), download speeds goes lower than 300Mbps after router TL-R605v1_un_1.0.0_20200930-rel36519_up. Download speeds...