Could not retrieve information from OPTIMADE

I am trying to make some queries using the OptimadeRester. But I am getting the following error. Here is the code snippet.

from pymatgen.ext.optimade import OptimadeRester
opt = OptimadeRester(‘cod’)
data = opt.get_snls(elements=[‘Li’,‘Mn’,‘O’], nelements=[1,3])
print(data)

I get the following error

Could not retrieve required information from provider cod and url https://www.crystallography.net/cod/optimade\v1/structures?filter=(elements HAS ALL "Li", "Mn", "O") AND (nelements>=1 AND nelements<=3)&response_fields=lattice_vectors,cartesian_site_positions,species,species_at_sites: HTTPSConnectionPool(host='www.crystallography.net', port=443): Read timed out. (read timeout=5)
{}

It also fails with other databases ‘mp’ and ‘aflow’ for example. Which could be the issue here?