That is the trade off. You many times have the choice of no internet or crappy internet provided by the mesh system.
Mesh you now have 2 radio signals so that alone is reducing your bandwidth by half. Then you have 2 signals that can now take interference from both inside and outside your house. In addition unless you buy the very expensive mesh systems that have extra backhual radio chips the unit actually interfere with each other.
These units are just the old generation repeater they have renamed mesh. You know it is now "new and improved", we put leds on it to make it faster
There is not real good solution. You can try other placement of the units. They must be cable to get strong signal from the main router and still send good signal to the remote area.
What you might consider is using some other technogy to connect between the main router and the remote units rather than using wifi. Best of course is ethernet but most people that buy repeaters don't have that. The next would be MoCA is you have coax cable in both rooms. MoCa can get gigabit speeds.
If that fails you can consider powerline networks. It won't be massively faster than what you have, maybe you get double but it will not drop as much as a mesh system.