I currently run a setup with a part of the network is connected to main network via a WDS bridge. Currently it uses only a 5G Network connection. Is it possible to add also a 2.5G WDS bridge with link aggregation to improve the performance?
Save yourself the trouble. Load balancing (especially with highly volatile links via wireless) is a nightmare to begin with, for miniscule gains (2.4 GHz is just so much slower to not be worth it).