Error downloading bonds because the list is too large for some countries

I am downloading bonds by country, the list of bonds from the US, CN and KR are too long for downloading, so I received different errors (Gateway Time-out, ) every time I try these countries. I was wondering which code kind I use to download these bonds by part if it is not possible to do it in bulk.

This is the code I am using:

#code for the fields

screen1 = 'SCREEN(U(IN(DEALS)/*UNV:DEALSBOND*/),TR.NIisECM=False, IN(TR.NINationHQ(NiDealPartRole=ISUP),'

screen2 = '), CURN=USD)'

#code for the fields

fields_firms = ['TR.NISdcPackageNumber',

'TR.NISdcPackageNumber.DealPackageID',

'TR.NISdcPackageNumber.DealId',

'TR.NISdcPackageNumber.IsTranchePrimary',

'TR.NISdcPackageNumber.SdcDealNumber',

'TR.NISDCTrancheId',

'TR.NIIssueDate',

'TR.NIRedemptionMaturityDate'

]

#code for parameters

parameters_screener = {'curn':'USD', 'NULL':'BLANK'}

ctry_code_list = ['US', 'CN' , 'KR']

# Retrieve firm list and info

firms_ric_list = {}

for ctry in ctry_code_list:

screen = screen1+ctry+screen2

df, err = ek.get_data(screen, fields_firms, parameters_screener)

with pd.ExcelWriter(os.path.join(d_bonds_dir,'screener_bonds_by_phyton.xlsx'), engine='openpyxl',mode='a') as writer:

df.to_excel(writer,sheet_name=ctry)

print(ctry)