The slower one was a Tmobile Revvl with (purchased high speed data):

• Quad Band GSM
• LTE: 2, 4, 5, 12, 66
• UMTS: Band II (1900), Band IV (1700/2100), Band V (850), Band VIII (900)

The bars never showed anything above 2G It did seem to help when I disabled background data.

The slightly faster one was an older windows phone, Lumia 550 one a Tmobile one plan:connectivity2GSM network: 850 MHz, 900 MHz, 1800 MHz, 1900 MHz
GSM max data speed DL: EGPRS 296.0 kbps
GSM max data speed UL: EGPRS 236.8 kbps
WCDMA network: Band 5 (850 MHz), Band 8 (900 MHz), Band 1 (2100 MHz)
WCDMA max data speed DL: 42.2 Mbps (Cat 24)
WCDMA max data speed UL: 5.76 Mbps (Cat 6)
LTE FDD network: Band 8 (900MHz), Band 20 (800MHz), Band 1 (2100 MHz), Band 3 (1800 MHz), Band 7 (2600 MHz)
LTE max data speed DL: 150 Mbps (Cat 4)
LTE max data speed UL: 50 Mbps (Cat 4)The bars never showed anything above E (?)

Annoying when you are trying to 'hail' an Uber driver.

Yeah I use cheap phones

Jim