Thermo-mechanical properties of polymer networks are known to depend on the functionality of monomer precursors -an association that is frequently exploited in materials science. We use molecular simulations to generate physical networks from chemically different monomers with identical functionality and show that such networks have several universal graphtheoretical properties as well as near universal Young's modulus, whereas the vitrification temperature is universal only up to a certain density of the network, as measured by the bond conversion. The latter observation is explained by noticing that monomer's tendency to coil is shown to enhance formation of topological holes, which, when accumulated in the network, result in a phase transition marked by the emergence of a percolating cell complex restricting network's mobility. This higher-order percolation occurs late after gelation and is shown to coincide with the onset of brittleness indicated by a sudden increase in the glass transition temperature.